2024年05月, 一般社団法人レーザー学会, 第44回学術講演会年次大会優秀論文発表賞　　　　　　　　　　　　　　　
和周波発生による周波数スイープパルス列生成を用いたsub-Gfpsシングルショットイメージング装置の開発
爲本 龍汰;漕江 駿太;本田 亜沙美;山根 啓作;戸田 泰則;尾松 孝茂;森田 隆二

High-definition direct-print of metallic microdots with optical vortex induced forward transfer
Rong Wei, Haruki Kawaguchi, Kaito Sato, Sayaka Kai, Keisaku Yamane, Ryuji Morita, Ken-ichi Yuyama, Satoyuki Kawano, Katsuhiko Miyamoto, Nobuyuki Aoki, Takashige Omatsu
APL Photonics, 9, 3, AIP Publishing, 2024年03月01日
研究論文（学術雑誌）, We demonstrate high-definition, direct-printing of micron-scale metallic dots, comprised of close-packed gold nanoparticles, by utilizing the optical vortex laser-induced forward transfer technique. We observe that the spin angular momentum of the optical vortex, associated with circular polarization, assists in the close-packing of the gold nanoparticles within the printed dots. The printed dots exhibit excellent electrical conductivity without any additional sintering processes. This technique of applying optical vortex laser-induced forward transfer to metallic dots is an innovative approach to metal printing, which does not require additional sintering. It also serves to highlight new insights into light–matter interactions.

Optical vortex induced spatio-temporally modulated superconductivity in a high-T_c cuprate
Yasunori Toda, Satoshi Tsuchiya, Keisaku Yamane, Ryuji Morita, Migaku Oda, Tohru Kurosawa, Tomaz Mertelj, Dragan Mihailovic
Optics Express, 31, 11, 17537, 17537, Optica Publishing Group, 2023年05月10日
研究論文（学術雑誌）, We report an experimental approach to produce spatially localized photoinduced superconducting state in a cuprate superconductor using optical vortices with ultrafast pulses. The measurements were carried out using coaxially aligned three-pulse time-resolved spectroscopy, in which an intense vortex pulse was used for coherent quenching of superconductivity and the resulting spatially modulated metastable states were analyzed by the pump-probe spectroscopy. The transient response after quenching shows a spatially localized superconducting state that remains unquenched at the dark core of the vortex beam for a few picoseconds. Because the quenching is instantaneously driven by photoexcited quasiparticles, the vortex beam profile can be transferred directly to the electron system. By using the optical vortex-induced superconductor, we demonstrate spatially resolved imaging of the superconducting response and show that the spatial resolution can be improved using the same principle as that of super-resolution microscopy for fluorescent molecules. The demonstration of spatially controlled photoinduced superconductivity is significant for establishing a new method for exploring novel photoinduced phenomena and applications in ultrafast optical devices.

Direct print of close-packed gold nanoparticle microdots with optical vortex illumination
Haruki Kawaguchi, Kanta Takahashi, Rong Wei, Keisaku Yamane, Ken-ichi Yuyama, Satoyuki Kawano, Ryuji Morita, Nobuyuki Aoki, Katsuhiko Miyamoto, Takashige Omatsu
Optical Manipulation and Structured Materials Conference (OMC 2022), SPIE, 2022年12月08日, ［査読有り］
研究論文（国際会議プロシーディングス）

Publisher Correction: Ultrafast beam pattern modulation by superposition of chirped optical vortex pulses.
Asami Honda, Keisaku Yamane, Kohei Iwasa, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
Scientific reports, 12, 1, 18674, 18674, 2022年11月04日, ［国際誌］
英語

Ultrafast beam pattern modulation by superposition of chirped optical vortex pulses.
Asami Honda, Keisaku Yamane, Kohei Iwasa, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
Scientific reports, 12, 1, 14991, 14991, 2022年09月02日, ［国際誌］
英語, 研究論文（学術雑誌）, As an extension of pulse shaping techniques using the space-time coupling of ultrashort pulses or chirped pulses, we demonstrated the ultrafast beam pattern modulation by the superposition of chirped optical vortex pulses with orthogonal spatial modes. The stable and robust modulations with a modulation frequency of sub-THz were carried out by using the precise phase control technique of the constituent pulses in both the spatial and time/frequency domains. The performed modulations were ultrafast ring-shaped optical lattice modulation with 2, 4 and 6 petals, and beam pattern modulations in the radial direction. The simple linear fringe modulation was also demonstrated with chirped spatially Gaussian pulses. While the input pulse energy of the pulses to be modulated was 360 [Formula: see text]J, the output pulse energy of the modulated pulses was 115 [Formula: see text]J with the conversion efficiency of [Formula: see text] 32%. Demonstrating the superposition of orthogonal spatial modes in several ways, this ultrafast beam pattern modulation technique with high intensity can be applicable to the spatially coherent excitation of quasi-particles or collective excitation of charge and spin with dynamic degrees of freedom. Furthermore, we analyzed the Poynting vector and OAM of the composed chirped OV pulses. Although the ring-shaped optical lattice composed of OV pulse with topological charges of [Formula: see text] is rotated in a sub-THz frequency, the net orbital angular momentum (OAM) averaged over one optical period is found to be negligible. Hence, it is necessary to require careful attention to the application of the OAM transfer interaction with matter by employing such rotating ring-shaped optical lattices.

Laser-induced forward-transfer with light possessing orbital angular momentum
Takashige Omatsu, Katsuhiko Miyamoto, Ken-Ichi Yuyama, Keisaku Yamane, Ryuji Morita
Journal of Photochemistry and Photobiology C: Photochemistry Reviews, 52, 100535, 100535, Elsevier BV, 2022年09月
研究論文（学術雑誌）

Lensless Wavefront Parallel Processing of Vector Beams by Self‐Images of a Self‐Organized Q‐Plates Microarray
Yuji Sasaki, Kenji Yamazaki, Naoshi Murakami, Keisaku Yamane, Hiroshi Orihara
Advanced Photonics Research, 3, 8, 2100368, 2100368, Wiley, 2022年08月, ［査読有り］, ［国際誌］
英語, 研究論文（学術雑誌）

Generation of hexagonal close-packed ring-shaped structures using an optical vortex
Haruki Kawaguchi, Kei Umesato, Kanta Takahashi, Keisaku Yamane, Ryuji Morita, Ken-ichi Yuyama, Satoyuki Kawano, Katsuhiko Miyamoto, Michinari Kohri, Takashige Omatsu
NANOPHOTONICS, 11, 4, 855, 864, WALTER DE GRUYTER GMBH, 2022年02月
英語, 研究論文（学術雑誌）, An optical vortex possesses a ring-shaped spatial profile and orbital angular momentum (OAM) owing to its helical wavefront. This form of structured light has garnered significant attention in recent years, and it has enabled new investigations in fundamental physics and applications. One such exciting application is laser-based material transfer for nano-/micro-fabrication. In this work, we demonstrate the application of a single-pulse optical vortex laser beam for direct printing of ring-shaped structures composed of hexagonal close-packed, mono-/multi-layered nanoparticles which exhibit 'structural color'. We compare and contrast the interaction of the vortex beam with both dielectric and metallic nanoparticles and offer physical insight into how the OAM of vortex beams interacts with matter. The demonstrated technique holds promise for not only photonic-based nano-/micro-fabrication, but also as a means of sorting particles on the nanoscale, a technology which we term 'optical vortex nanoparticle sorting'.

Direct Optical Vortex Laser Printing of a Microdot with Close-Packed and Sintered Gold Nanoparticles
Haruki Kawaguchi, Rong Wei, Keisaku Yamane, Ken-ichi Yuyama, Satoyuki Kawano, Ryuji Morita, Kohei Toyoda, Katsuhiko Miyamoto, Takashige Omatsu
Conference on Lasers and Electro-Optics, Optica Publishing Group, 2022年
研究論文（国際会議プロシーディングス）, We demonstrate the direct printing of an ultrafine microdot formed of gold nanoparticles by employing optical vortex laser induced forward transfer. Spin and orbital angular momentum induces the close-packing and sintering of gold nanoparticles.

Development of sub-Gfps ultrafast snapshot imaging system based on recirculation filtering of ultrashort optical pulses
Asami Honda, Keisaku Yamane, Masato Suzuki, Jin Kawaguchi, Yasunori Toda, Takashige Omatsu, Ryuji Morita
Optics InfoBase Conference Papers, 2022年
研究論文（国際会議プロシーディングス）, We demonstrated ultrafast snapshot imaging with a sub-GHz framerate on the basis of our newly proposed recirculation-filtering method, which enables us to generate a wavelength-division multiplexed pulse train with a time interval in nanosecond regime.

Development of sub-Gfps ultrafast snapshot imaging system based on recirculation filtering of ultrashort optical pulses
Asami Honda, Keisaku Yamane, Masato Suzuki, Jin Kawaguchi, Yasunori Toda, Takashige Omatsu, Ryuji Morita
2022 Conference on Lasers and Electro-Optics, CLEO 2022 - Proceedings, 2022年
研究論文（国際会議プロシーディングス）, We demonstrated ultrafast snapshot imaging with a sub-GHz framerate on the basis of our newly proposed recirculation-filtering method, which enables us to generate a wavelength-division multiplexed pulse train with a time interval in nanosecond regime.

Ultrafast snapshot imaging at sub-GHz framerate by using recirculation filtering of ultrashort optical pulses
Asami Honda, Ryota Tamemoto, Keisaku Yamane, Masato Suzuki, Yasunori Toda, Takashige Omatsu, Ryuji Morita
Optics InfoBase Conference Papers, 2022年
研究論文（国際会議プロシーディングス）, We successfully demonstrated ultrafast snapshot imaging based on time-to-frequency mapping method with four frames and ∼ 5.5 ns time interval (i.e. sub-GHz framerate) by using our newly-developed recirculation system without ultrafast image sensor.

Coherent quench of superconducting state using optical vortex pulses
Y. Toda, S. Tsuchiya, K. Yamane, R. Morita, M. Oda, T. Mertelj, D. Mihailovic
Optics InfoBase Conference Papers, 2022年
研究論文（国際会議プロシーディングス）, Recently, topological lightwaves, represented by optical vortices, have become easily generated and are expected to have many novel applications. In this work, we report on coherent quench spectroscopy of a cuprate superconductor using optical vortex pulses to reveal the spatially modulated superconducting (SC) state. The transient response after quenching by the optical vortex pulse shows the spatially localized SC response that remains unquenched around the dark spot of the optical vortex. The spatially resolved imaging of the optical vortex-induced SC improves the spatial resolution in a similar principle to super-resolution microscopy.

Coherent quench of superconducting state using optical vortex pulses
Y. Toda, S. Tsuchiya, K. Yamane, R. Morita, M. Oda, T. Mertelj, D. Mihailovic
2022 Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2022 - Proceedings, 2022年
研究論文（国際会議プロシーディングス）, Recently, topological lightwaves, represented by optical vortices, have become easily generated and are expected to have many novel applications. In this work, we report on coherent quench spectroscopy of a cuprate superconductor using optical vortex pulses to reveal the spatially modulated superconducting (SC) state. The transient response after quenching by the optical vortex pulse shows the spatially localized SC response that remains unquenched around the dark spot of the optical vortex. The spatially resolved imaging of the optical vortex-induced SC improves the spatial resolution in a similar principle to super-resolution microscopy.

Ultrafast snapshot imaging at sub-GHz framerate by using recirculation filtering of ultrashort optical pulses
Asami Honda, Ryota Tamemoto, Keisaku Yamane, Masato Suzuki, Yasunori Toda, Takashige Omatsu, Ryuji Morita
2022 Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2022 - Proceedings, 2022年
研究論文（国際会議プロシーディングス）, We successfully demonstrated ultrafast snapshot imaging based on time-to-frequency mapping method with four frames and ∼ 5.5 ns time interval (i.e. sub-GHz framerate) by using our newly-developed recirculation system without ultrafast image sensor.

Propagation-invariant vortex Airy beam whose singular point follows its main lobe
Masato Suzuki, Keisaku Yamane, Takashige Omatsu, Ryuji Morita
NEW JOURNAL OF PHYSICS, 23, 11, IOP Publishing Ltd, 2021年11月
英語, 研究論文（学術雑誌）, We propose and demonstrate a novel vortex Airy beam which is a superposition of an Airy beam and its laterally sheared beam with a pi/2 phase shift. This new-type of vortex Airy beam exhibits stable propagation dynamics, wherein its singular point closely follows its main lobe, unlike conventional vortex Airy beams. Notably, the orbital angular mode purity of this new vortex Airy beam is up to 10% better than that of a conventional vortex Airy beam. We anticipate that this new type of vortex Airy beam, which combines the characteristics of an optical vortex and a diffraction-free Airy beam, will facilitate new directions in applications such as microscopy, material processing and nonlinear optics.

Optical vortex induced microdroplet with a plasmonic nanocore
Haruki Kawaguchi, Kei Umesato, Kanta Takahashi, Keisaku Yamane, Ken-ichi Yuyama, Satoyuki Kawano, Katsuhiko Miyamoto, Takadhige Omatsu
Optical Manipulation and Structured Materials Conference 2021, SPIE, 2021年10月27日
研究論文（国際会議プロシーディングス）

Vortex Airy beam realized by superposition of two Airy beams
Masato Suzuki, Keisaku Yamane, Takashige Omatsu, Ryuji Morita
Optics InfoBase Conference Papers, 2021年
研究論文（国際会議プロシーディングス）, We propose a new-type vortex Airy beam with both orbital angular momentum and non-diffraction property as a superposition of laterally-sheared two Airy beams. The propagation characteristics are hugely improved compared with the conventional ones.

Spectroscopic polarization measurement and control using channeled spectrum
Kazuhiko Oka, Keisaku Yamane, Moritsugu Sakamoto, Ryuji Morita
Proceedings of SPIE - The International Society for Optical Engineering, 11927, 2021年
研究論文（国際会議プロシーディングス）, Spectroscopic polarization measurement and control using channeled spectrum has several unique features and is useful for various spectroscopic instruments. It utilizes the strong dispersion characteristics in polarization retardation of high-order retarders so that the polarization modulation can be made without using mechanical or active elements for polarization modulation. In this presentation, we describe its principle, basic features, and several applications including a spectroscopic ellipsometer and ultrafast rotations of beam profile and polarization.

Laguerre-Gaussian vortex mode generation from astigmatic semiconductor microcavity
Kohki Nakagawa, Keisaku Yamane, Ryuji Morita, Yasunori Toda
APPLIED PHYSICS EXPRESS, 13, 4, 042001/1, 5, IOP PUBLISHING LTD, 2020年04月, ［査読有り］
英語, 研究論文（学術雑誌）, Laguerre-Gaussian (LG) vortex mode generations are demonstrated by employing the optical injection of a higher-order transverse mode into a vertical cavity surface emitting laser. In addition to the coherent LG injection, Hermite-Gaussian (HG) injection also enable LG mode generation, where the chirality is controllable by the HG mode angle of the injection beam. The result can be well understood when we consider the astigmatic Gouy phase shifts within the microcavity. HG induced vortex generation eases the symmetrical requirements of the cavity and thus extends flexibility as regards the design and fabrication of vortex lasers.

Ultrafast azimuth rotation of linearly polarized beam by use of a chirped optical pulse pair
Rin Sasaki, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda, Takashige Omatsu, Ryuji Morita
Proceedings of SPIE - The International Society for Optical Engineering, 11522, 2020年
研究論文（国際会議プロシーディングス）, We demonstrated that ultrafast azimuth rotation of linearly polarized beam by use of a chirped optical pulse pair, and the rotational frequency of sub-THz was realized.

Two photon-induced chiral structures of azo-polymers
Ami Shiraishi, Keigo Masuda, Keisaku Yamane, Kohei Toyoda, Katsuhiko Miyamoto, Takashige Omatsu
2020 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), IEEE, 2020年
英語, 研究論文（国際会議プロシーディングス）, We demonstrate the formation of chiral surface structure of azo-polymers via optical vortex induced two-photon-absorption (TPA). TPA-induced isomerization allows us to create the three-dimensional chiral structures with high longitudinal and transverse spatial resolution beyond the diffraction limit. (c) 2020 The Author(s)

Fractional optical vortex creates a curved spin-jet
Haruki Kawaguchi, Kei Umesato, Keisaku Yamane, Katsuhiko Miyamoto, Takashige Omatsu
Proceedings of SPIE - The International Society for Optical Engineering, 11522, SPIE-INT SOC OPTICAL ENGINEERING, 2020年
英語, 研究論文（国際会議プロシーディングス）, We discover an entirely novel phenomenon, so-called the formation of curved "spin-jet", in which an irradiated fractional optical vortex provides a donor film non-axisymmetric torque to form a "spin-jet" with a curved trajectory. This phenomenon allows the development of a novel pattering technology to scan the ejected donor dots without any mechanical systems.

Two photon-induced chiral structures of azo-polymers
Ami Shiraishi, Keigo Masuda, Keisaku Yamane, Kohei Toyoda, Katsuhiko Miyamoto, Takashige Omatsu
Optics InfoBase Conference Papers, Part F183-CLEO-SI 2020, 2020年
研究論文（国際会議プロシーディングス）, We demonstrate the formation of chiral surface structure of azo-polymers via optical vortex induced two-photon-absorption (TPA). TPA-induced isomerization allows us to create the three-dimensional chiral structures with high longitudinal and transverse spatial resolution beyond the diffraction limit.

Picosecond optical vortex-induced chiral surface relief in an azo-polymer film
Keigo Masuda, Ryo Shinozaki, Ami Shiraishi, Mitsuki Ichijo, Keisaku Yamane, Katsuhiko Miyamoto, Takashige Omatsu
Journal of Nanophotonics, 14, 1, SPIE-SOC PHOTO-OPTICAL INSTRUMENTATION ENGINEERS, 2020年01月01日
英語, 研究論文（学術雑誌）, We report on the first demonstration of picosecond optical vortex-induced chiral surface relief in an azo-polymer film due to two-photon absorption isomerization. The chiral surface relief exhibits an extremely narrow defocusing tolerance without undesired outer rings due to the Airy pattern of highly focused light. Such chiral surface relief reflects a z-polarized electric field with an azimuthal helical phase caused by spin-orbital angular momentum coupling.

Comprehensive quantitative analysis of vector beam states based on vector field reconstruction
Masato Suzuki, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
Scientific Reports, 9, 1, NATURE PUBLISHING GROUP, 2019年12月01日, ［査読有り］
英語, 研究論文（学術雑誌）, We demonstrate a comprehensive quantitative analysis of vector beam states (VBSs) by using a vector field reconstruction (VFR) technique integrating interferometry and imaging polarimetry, where the analysis is given by a cylindrically polarized Laguerre–Gaussian (LG) mode expansion of VBSs. From test examples of cylindrically polarized LG mode beams, we obtain the complex amplitude distributions of VBSs and perform their quantitative evaluations both in radial and azimuthal directions. The results show that we generated (l, p) = (1, 0) LG radially polarized state with a high purity of 98%. We also argue that the cylindrically polarized LG modal decomposition is meaningful for the detail discussion of experimental results, such as analyses of mode purities and mode contaminations. Thus the VFR technique is significant for analyses of polarization structured beams generated by lasers and converters.

Chiral mass-transport of azo-polymers with OAM light field through two photon absorption
Keigo Masuda, Mitsuki Ichijo, Ryo Shinozaki, Keisaku Yamane, Katsuhiko Miyamoto, Takashige Omatsu
Proceedings of SPIE - The International Society for Optical Engineering, 11141, 2019年
研究論文（国際会議プロシーディングス）, We demonstrate chiral mass-transport of azo-polymers by illumination of tightly focused 1-μm picosecond optical vortex pulses with a pulse width of 8-ps through two-photon absorption. The chiral surface relief formation requires picosecond pulses with a relatively long pulse duration. In fact, it is also worth noting that it is difficult to create such chiral surface relief by employing 2-ps optical vortex pulses.

Efficient generation of intense spatio-temporally controlled light waves
Keisaku Yamane, Kohei Iwasa, Rin Sasaki, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
Proceedings of SPIE - The International Society for Optical Engineering, 11141, 2019年
研究論文（国際会議プロシーディングス）, We developed the high-efficiency beam converter for ultrafast spatio-temporal control of light waves based on Sagnac interferometer. The flexible control both in the azimuth and radial directions in the ultrafast regime was also realized.

Two-photon induced helical relief in azo-polymer film
Keigo Masuda, Mitsuki Ichijo, Ryo Sinozaki, Keisaku Yamane, Katsuhiko Miyamoto, Takashige Omatsu
Optics InfoBase Conference Papers, Part F146-JSAP 2019, 2019年
研究論文（国際会議プロシーディングス）

Vortex mode emission properties of vertical cavity surface emitting laser with external optical feedback
Y. Toda, K. Nakagawa, K. Yamane, R. Morita, Y. Awaji
Proceedings of SPIE - The International Society for Optical Engineering, 11141, 2019年
研究論文（国際会議プロシーディングス）, Based on our previous work, in which we demonstrated single orbital angular momentum (OAM) mode emissions from a vertical cavity surface emitting laser (VCSEL) with an external optical feedback, the conditions of the vortex mode emission are investigated in terms of feedback efficiency and polarization. There are two orthogonal polarization configurations for efficient single OAM mode emission, one of which corresponds to the dominant polarization in freerunning VCSEL. Nearly identical emission properties of the two polarizations indicate an independence between the spin and OAM. On the other hand, the stability of the OAM mode emission, which is characterized by the dependencies of the feedback efficiency and injection current, is changed between the two polarizations, suggesting different contributions of the broken rotational symmetry to the spin and OAM.

Development of high-efficiency beam converter for ultrafast spatio-temporal control of light waves
Keisaku Yamane, Kohei Iwasa, Rin Sasaki, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
Optics InfoBase Conference Papers, Part F140-CLEO_Europe 2019, 2019年
研究論文（国際会議プロシーディングス）, When two optical vortices with different topological charges mutually interfere, azimuthally periodic structure called a ring-shaped optical lattice is formed [1]. The petal-like beam profile can be flexibly rotated by controlling the intermodal phase difference, which offers us rotational degree of freedom in applications such as optical manipulations of micro/nano particles and micro machines. However, their maximum rotational frequency has been limited to GHz regime owing to their response time or bandwidth. Recently, we succeeded in drastically increasing the rotational frequency up to THz regime by introducing a new technique based on spatial mode multiplexing of chirped optical-vortex pair [2].

Improvement of resolution in orbital angular momentum decomposition based on beam duplication by using a Sagnac interferometer
Keisaku Yamane, Yuho Watanabe, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
Optics InfoBase Conference Papers, Part F140-CLEO_Europe 2019, 2019年
研究論文（国際会議プロシーディングス）, Recently, the spatial mode multiplexing based on optical vortices (OVs) attracts much attentions as a promissing technology for high-capacity optical communications. For such OV-based telecommunications, optical components for mode decomposition with respect to azimuth mode indices (topological charges) - so-called orbital angular momentum (OAM) sorters - are key devices, and various kinds of OAM sorters have been demonstrated such as computer-generated holograms as far. Among them, the geometric transformation (GT) technique has great advantages that the insertion loss is quite low and it supports inverse transformation (multiplexing) [1]. In earlier studies, GT-based OAM sorters have been realized by using spatial light modulators (SLMs) [1], and more recently, transparent refractive elements produced by using such as diamond machining [2] and Pancharatnam Berry phase [3] have been demonstrated. However, the GT-based method has the serious disadvantage of relatively large crosstalk between the neighboring modes. In order to overcome the problems, the beam copying technique by using diffractive optics was demonstrated [4]. The novel technique can greatly reduce the crosstalk between the OAM modes, but spoils the advantage that the OAM sorter can support the low-loss inverse transformation. In this paper, we demonstrate the new beam duplication technique by using a Sagnac interferometer, which can improve the resolution in the OAM mode decomposition and also support low-loss inverse transformation.

Two-photon induced chiral mass-transport of azo-polymers as a function of pulse duration
Keigo Masuda, Yoshinori Kinezuka, Mitsuki Ichijo, Ryo Shinozaki, Keisaku Yamane, Kouhei Toyoda, Katsuhiko Miyamoto, Takashige Omatsu
Optics InfoBase Conference Papers, Part F129-CLEO_SI 2019, 2019年, ［査読有り］
研究論文（国際会議プロシーディングス）, We have demonstrated two-photon-absorption induced chiral surface relief formation in an azo-polymer film by the illumination of picosecond 1-μm optical vortex pulses. The chiral surface relief formation required at least several times the response time of trans-cis isomerization of the azo-polymers. The resulting chiral surface relief exhibited a diameter of 3-μm, corresponding to 0.7 times the diffraction limit. We also observed spin-orbital angular momentum coupling in the surface relief formation, even via two-photon-absorption.

トポロジカル光波の発生・計測技術
山根啓作
電子情報通信学会論文誌 C(Web), J101-C, 12, 509‐517 (WEB ONLY), 2018年12月01日
日本語

Generation of arbitrary axisymmetrically polarized pulses by using the combination of 4- f spatial light modulator and common-path optical system
Masato Suzuki, Keisaku Yamane, Moritsugu Sakamoto, O. K.A. Kazuhiko, Yasunori Toda, Ryuji Morita
Optics Express, 26, 3, 2584, 2598, OPTICAL SOC AMER, 2018年02月05日, ［査読有り］
英語, 研究論文（学術雑誌）, We proposed and constructed a system to realize broadband generation of arbitrary axisymmetrically polarized (AP) pulses with spatial complex amplitude modulation. This system employs the combination of a spatial light modulator in the 4- fconfiguration (4- fSLM), and a space variant wave plate as a common path interferometer. The 4- f SLM and the common path interferometer o er compensation for spatial dispersion with respect to wavelength and stability to perturbation, respectively. We experimentally demonstrated the various AP pulses generation by applying modulations of fundamental and higher-order Laguerre-Gauss modes, whose radial indices were, respectively, p=0 and 1, with high purity, which showed that we were able to generate arbitral AP pulses with spatial complex amplitude modulation. This technique is expected to be applied in both classical and quantum communications with higher-order modes.

Development of high-precision mode decomposition devices for optical vortices
Keisaku Yamane, Yuho Watanabe, Isamu Wakisaka, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
Optics InfoBase Conference Papers, Part F114-FIO 2018, 2018年
研究論文（国際会議プロシーディングス）, New mode decomposition devices for optical vortices were developed. Their performances were experimentally verified and in good agreement with the corresponding simulations, showing precise spatial-phase control based on Pancharatnam-Berry phase.

Generation of arbitrary axisymmetrically polarized pulses with a broadband spectrum
Ryuji Morita, Masato Suzuki, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda
Proceedings of SPIE - The International Society for Optical Engineering, 10549, SPIE-INT SOC OPTICAL ENGINEERING, 2018年, ［査読有り］
英語, 研究論文（国際会議プロシーディングス）, Subsequently to the previous generation of ultrashort and ultra-broadband optical-vortex (OV) pulses (pulse energy: several tens of μJ) in few-cycle regime, we performed the generation of axisymmetrically polarized pulses with spatial complex amplitude modulation, which is suitable for a broadband spectrum. The generation system employs the combination of spatial light modulators in the 4-f configuration and a space variant wave plate as a common path interferometer. The spatial light modulators in the 4-f configuration offer the spatial dispersion compensation with respect to wavelength; in addition, the common path interferometer provides the stability to perturbation. We experimentally demonstrated the generation of various axisymmetrically polarized pulses by applying modulations of fundamental and higher-order Laguerre-Gauss modes with high purity. The experimental results show that we are able to generate arbitral axisymmetrically polarized pulses with spatial complex amplitude modulation.

光波の空間モードを制御する~光渦を中心に~超広帯域光渦パルスの定量的評価法=光電場再生を用いた高速・高精度計測=
山根啓作, 森田隆二
光アライアンス, 28, 9, 31‐35, 30, 日本工業出版, 2017年09月
日本語, 研究論文（学術雑誌）

超広帯域光渦パルスの定量的評価法 : 光電場再生を用いた高速・高精度計測 (特集 光波の空間モードを制御する : 光渦を中心に)
山根 啓作, 森田 隆二
光アライアンス, 28, 9, 31, 35, 日本工業出版, 2017年09月
日本語

Single orbital angular mode emission from externally feed-backed vertical cavity surface emitting laser
Y. Toda, A. Moriya, K. Yamane, R. Morita, K. Shigematsu, Y. Awaji
APPLIED PHYSICS LETTERS, 111, 10, AMER INST PHYSICS, 2017年09月
英語, 研究論文（学術雑誌）, The single orbital angular momentum mode emission from a commercially available broad-area vertical cavity surface emitting laser (VCSEL) is realized with an optical feedback technique using a spatial light modulator, where a computer generated hologram (CGH) is optimized by taking into account the mode properties of the external cavity VCSEL. The flexibility with which the chirality of the orbital angular momentum mode can be selected is also demonstrated simply by changing the chirality of the CGH. The technique is very simple and easily applicable to other VCSELs without processing. (C) 2017 Author(s).

Amplification of ultrafast-rotating ring-shaped optical lattices
Keisaku Yamane, Kohei Iwasa, Kohei Kakizawa, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
2017 CONFERENCE ON LASERS AND ELECTRO-OPTICS EUROPE & EUROPEAN QUANTUM ELECTRONICS CONFERENCE (CLEO/EUROPE-EQEC), IEEE, 2017年, ［査読有り］
英語, 研究論文（国際会議プロシーディングス）

Single orbital angular momentum mode emission from vertical cavity surface emitting laser by optical feedback
Y. Toda, H. Moriya, K. Shigematsu, K. Yamane, R. Morita, Y. Awaji
OPTICAL MANIPULATION CONFERENCE, 10252, SPIE-INT SOC OPTICAL ENGINEERING, 2017年, ［査読有り］
英語, 研究論文（国際会議プロシーディングス）, Single angular momentum (OAM) mode emissions from a vertical cavity surface emitting laser (VCSEL) were demonstrated by an external optical feedback using computer generated holograms, which are optimized on the OAM modal gain of the free-running VCSEL. Side-mode suppression ratio of more than 23 dB was achieved for the OAM modes with l = +/- 1.

Generation of intense ultrafast-rotating ring-shaped optical lattices with programmable control of rotational symmetry
Keisaku Yamane, Kohei Iwasa, Kohei Kakizawa, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
OPTICAL MANIPULATION CONFERENCE, 10252, SPIE-INT SOC OPTICAL ENGINEERING, 2017年, ［査読有り］
英語, 研究論文（国際会議プロシーディングス）, A new method for the ultrafast rotation of ring-shaped optical lattices based on frequency-chirping of optical pulses was demonstrated in THz regime, which is three orders of magnitude faster than those by the conventional methods. Our optical lattice generator with a spatial light modulator is robust thanks to the 4-f configuration and enables us to flexibly control their rotational symmetry. The generated ultrafast-rotating ring-shaped optical lattices with a rotational frequency of 0.59 THz were successfully boosted from 5 mu J up to 125 mu J by using a home-built 4-pass Ti:sapphire amplifier without any limitation by optical damage to the spatial light modulator.

Snap-shot optical polarization spectroscopy using radially polarized pulses
Kyohhei Shigematsu, Masato Suzuki, Keisaku Yamane, Ryuji Morita, Yasunori Toda
APPLIED PHYSICS EXPRESS, 9, 12, IOP PUBLISHING LTD, 2016年12月
英語, 研究論文（学術雑誌）, By using radially polarized pulses for excitation in degenerate four-wave mixing (DFWM) spectroscopy, we realize highly sensitive snap-shot measurement of optical anisotropies in semiconductor films. Because the radially polarized pulses exhibit spatially varying linear polarizations, the optical anisotropies in samples can be evaluated from the spatial distributions of DFWM signals without rotating the polarization of the excitation pulses. We measure the excitons in GaN layers and evaluate the energies of uniaxial strain and the spin-exchange interaction constant. Our results prove both the accuracy and sensitivity of the snap-shot measurement. (C) 2016 The Japan Society of Applied Physics

Analysis of the Pancharatnam-Berry phase of vector vortex states using the Hamiltonian based on the Maxwell-Schrödinger equation
Masato Suzuki, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
Physical Review A - Atomic, Molecular, and Optical Physics, 94, 2016年10月26日
© 2016 American Physical Society.We derived the Berry connection of vector vortex states (VVSs) from the "true" Hamiltonian obtained through the Maxwell-Schrödinger equation for an inhomogeneous anisotropic (IA) medium, and we experimentally demonstrated measurement of the corresponding Pancharatnam-Berry (PB) geometrical phase of VVSs. The PB phase (PBP) of VVSs can be divided into two phases: homogeneous and inhomogeneous PBPs. Homogeneous and inhomogeneous PBPs are related to the conventional PBP and the spatially dependent geometric phase given by an IA medium such as a polarization converter, respectively. We theoretically detected that inhomogeneous PBP accumulation originates from the gauge dependence of the index of the hybrid-order Poincaré sphere, which provides an alternate method for understanding optical spin-orbital angular momentum conversion. The homogeneous PBP, which is explicitly observed, has implications for quantum-state manipulation and information processing.

Analysis of the Pancharatnam-Berry phase of vector vortex states using the Hamiltonian based on the Maxwell-Schrodinger equation
Masato Suzuki, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
PHYSICAL REVIEW A, 94, 4, AMER PHYSICAL SOC, 2016年10月, ［査読有り］
英語, 研究論文（学術雑誌）, We derived the Berry connection of vector vortex states (VVSs) from the "true" Hamiltonian obtained through the Maxwell-Schrodinger equation for an inhomogeneous anisotropic (IA) medium, and we experimentally demonstrated measurement of the corresponding Pancharatnam-Berry (PB) geometrical phase of VVSs. The PB phase (PBP) of VVSs can be divided into two phases: homogeneous and inhomogeneous PBPs. Homogeneous and inhomogeneous PBPs are related to the conventional PBP and the spatially dependent geometric phase given by an IA medium such as a polarization converter, respectively. We theoretically detected that inhomogeneous PBP accumulation originates from the gauge dependence of the index of the hybrid-order Poincare sphere, which provides an alternate method for understanding optical spin-orbital angular momentum conversion. The homogeneous PBP, which is explicitly observed, has implications for quantum-statemanipulation and information processing.

Picosecond rotation of a ring-shaped optical lattice by using a chirped vortex-pulse pair
K. Yamane, M. Sakamoto, N. Murakami, R. Morita, K. Oka
OPTICS LETTERS, 41, 19, 4597, 4600, OPTICAL SOC AMER, 2016年10月
英語, 研究論文（学術雑誌）, A novel method of ultrafast rotation of a ring-shaped optical lattice in the picosecond time region was proposed and demonstrated. Our ring-lattice generator was assembled by a pair of linearly chirped pulses with a time delay, a high-order birefringent retarder, and an axially symmetric polarization element. Using a mode-locked Ti:sapphire laser oscillator as a light source, stable two-, four-, and six-petaled ring-lattice rotations were demonstrated with the rotation periods of 1.6, 3.2, and 4.8 ps, respectively. Our method has the potential to open up a new technique to resonantly excite propagating quasi- particles together with their coherent enhancement. (C) 2016 Optical Society of America

Picosecond optical vortex pulse illumination forms a monocrystalline silicon needle
Fuyuto Takahashi, Katsuhiko Miyamoto, Hirofumi Hidai, Keisaku Yamane, Ryuji Morita, Takashige Omatsu
SCIENTIFIC REPORTS, 6, 21738, NATURE PUBLISHING GROUP, 2016年02月, ［査読有り］
英語, 研究論文（学術雑誌）, The formation of a monocrystalline silicon needle by picosecond optical vortex pulse illumination was demonstrated for the first time in this study. The dynamics of this silicon needle formation was further revealed by employing an ultrahigh-speed camera. The melted silicon was collected through picosecond pulse deposition to the dark core of the optical vortex, forming the silicon needle on a submicrosecond time scale. The needle was composed of monocrystalline silicon with the same lattice index (100) as that of the silicon substrate, and had a height of approximately 14 mu m and a thickness of approximately 3 mu m. Overlaid vortex pulses allowed the needle to be shaped with a height of approximately 40 mu m without any changes to the crystalline properties. Such a monocrystalline silicon needle can be applied to devices in many fields, such as core-shell structures for silicon photonics and photovoltaic devices as well as nano- or microelectromechanical systems.

Coherent dynamics of exciton orbital angular momentum transferred by optical vortex pulses
K. Shigematsu, K. Yamane, R. Morita, Y. Toda
Physical Review B - Condensed Matter and Materials Physics, 93, 2016年01月15日
© 2016 American Physical Society. The coherent dynamics of the exciton center-of-mass motion in bulk GaN are studied using degenerate four-wave-mixing (FWM) spectroscopy with Laguerre-Gaussian (LG) mode pulses. We evaluate the exciton orbital angular momentum (OAM) dynamics from the degree of OAM, which is derived from the distributions of OAM (topological charge) of the FWM signals. When excitons are excited with two single-mode LG pulses, the exciton OAM decay time significantly exceeds the exciton dephasing time, which can be attributed to high uniformity of the exciton dephasing in our bulk sample because the decoherence of the exciton OAM is governed by the angular variation in the exciton dephasing. We also analyze the topological charge (ℓ) dependence of the OAM decay using a multiple-mode LG pump pulse, which allows us to simultaneously observe the dynamics of the exciton OAM for different ℓ values under the same excitation conditions. The OAM decay times of the ℓ=1 component are usually longer than those of the ℓ=0 component. The ℓ-dependent OAM decay is supported by a phenomenological model which takes into account the local nonuniformity of the exciton dephasing.

ポアンカレビームパルスを用いたGaN励起子スピンのコヒーレントダイナミクス観測
内古閑 隆太郎, 重松 恭平, 山根 啓作, 森田 隆二, 戸田 泰則
日本物理学会講演概要集, 71, 2, 1414, 1414, 一般社団法人 日本物理学会, 2016年
日本語,

ビーム断面上の偏光分布が二回対称で、直線偏光と円偏光を同時に持つポアンカレビームパルスを励起光に用いると、異なるスピン状態を持つ励起子の同時励起が可能である。本研究では、縮退四光波混合分光を用いたバルクGaN励起子励起およびストークス分解検出を行い、励起子スピンのコヒーレントダイナミクス測定を実現した。得られた信号光の空間偏光分布はT2時間内で励起光を良く反映しており、励起子スピンのコヒーレント状態保持を示すことができた。

Coherent dynamics of exciton orbital angular momentum transferred by optical vortex pulses
K. Shigematsu, K. Yamane, R. Morita, Y. Toda
PHYSICAL REVIEW B, 93, 4, AMER PHYSICAL SOC, 2016年01月, ［査読有り］
英語, 研究論文（学術雑誌）, The coherent dynamics of the exciton center-of-mass motion in bulk GaN are studied using degenerate four-wave-mixing (FWM) spectroscopy with Laguerre-Gaussian (LG) mode pulses. We evaluate the exciton orbital angular momentum (OAM) dynamics from the degree of OAM, which is derived from the distributions of OAM (topological charge) of the FWM signals. When excitons are excited with two single-mode LG pulses, the exciton OAM decay time significantly exceeds the exciton dephasing time, which can be attributed to high uniformity of the exciton dephasing in our bulk sample because the decoherence of the exciton OAM is governed by the angular variation in the exciton dephasing. We also analyze the topological charge (l) dependence of the OAM decay using a multiple-mode LG pump pulse, which allows us to simultaneously observe the dynamics of the exciton OAM for different l values under the same excitation conditions. The OAM decay times of the l = 1 component are usually longer than those of the l = 0 component. The l-dependent OAM decay is supported by a phenomenological model which takes into account the local nonuniformity of the exciton dephasing.

Full Quantitative Analysis of Arbitrary Cylindrically Polarized Pulses by Using Extended Stokes Parameters
Masato Suzuki, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
SCIENTIFIC REPORTS, 5, 17797, NATURE PUBLISHING GROUP, 2015年12月, ［査読有り］
英語, 研究論文（学術雑誌）, Cylindrically polarized (CP) modes are laser beam modes which have rotational symmetry of the polarization distribution around the beam axis. Considerable attention has been paid to CP modes for their various applications. In this paper, by using the extended Stokes parameters and the degree of polarization defined for the spatial distribution (DOP-SD), we fully-quantitatively characterize the spectrally-resolved polarization states of arbitrary CP (axisymmetrically polarized and higher-order cylindrically polarized) broadband pulses generated by coherent beam combining. All the generated pulse states were fully-quantitatively analyzed for the first time and proved to have high symmetry (DOP-SD greater than or similar to 0.95) and low spectral dependence of polarization states. Moreover, we show the DOP-SD, which cannot be defined by the conventional higher-order and hybrid Stokes parameters, enables us to make a quantitative evaluation of small degradation of rotational symmetry of polarization distribution. This quantitative characterization with high precision is significant for applications of precise material processing, quantum information processing, magneto-optical storage and nonlinear spectroscopic polarimetry.

軸対称偏光素子を用いた光渦の生成と白色光渦およびリング状光格子生成への応用 (特集 広がりを見せる光渦)
岡 和彦, 坂本 盛嗣, 山根 啓作
O plus E : Optics・Electronics, 37, 4, 263, 268, アドコム・メディア, 2015年04月
日本語

Extended Stokes parameters for cylindrically polarized beams
Masato Suzuki, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
OPTICAL REVIEW, 22, 1, 179, 183, OPTICAL SOC JAPAN, 2015年02月
英語, 研究論文（学術雑誌）, The extended Stokes parameters for arbitrary cylindrically polarized beams are newly introduced to evaluate their quality. A set of the parameters, expressing a cylindrically polarized state, permits the definition of the degree of polarization that indicates the purity of the spatial symmetry of polarization of a light beam. In addition, the Pancharatnam-Berry phase related to the cylindrically polarized states is described by the new Stokes parameters.

Quantitative characterization of polarization states of axisymmetrically polarized pulses generated by coherent beam combining
Masato Suzuki, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
2015 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), IEEE, 2015年, ［査読有り］
英語, 研究論文（国際会議プロシーディングス）, By using the extended Stokes parameters and the degree of polarization defined for the spatial distribution (DOP-SD), we fully quantitatively characterize the polarization states of arbitrary (DOP-SD> 0.96) axisymmetrically-polarized femtosecond pulses generated by coherent beam combining. (C) 2014 Optical Society of America

Coherent dynamics of uniaxially-strained GaN excitons excited by cylindrically polarized pulses　　　　　　　　　　　　　　　
K. Shigematsu, S. Morimoto, M. Suzuki, K. Yamane, R. Morita, Y. Toda
Optics InfoBase Conference Papers, OSA - The Optical Society, 2014年07月21日
英語, 研究論文（国際会議プロシーディングス）

Eigenmode expansion of optical vortices based on electric-field reconstruction in spatial domain　　　　　　　　　　　　　　　
Keisaku Yamane, Shota Nakajima, Masato Suzuki, Yasunori Toda, Ryuji Morita
Optics InfoBase Conference Papers, OSA - The Optical Society, 2014年07月21日
英語, 研究論文（国際会議プロシーディングス）

Nonlinear coupling between axisymmetrically-polarized ultrashort optical pulses in a uniaxial crystal
Masato Suzuki, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
OPTICS EXPRESS, 22, 14, 16903, 16915, OPTICAL SOC AMER, 2014年07月, ［査読有り］
英語, 研究論文（学術雑誌）, Nonlinear propagation of focused axisymmetrically-polarized ultrashort optical pulses along the optic axis in a uniaxial crystal is investigated experimentally and theoretically. The energy transfer between an azimuthally-polarized pulse and a radially-polarized pulse is observed. To analyze the nonlinear propagation, a general paraxial equation with a third-order nonlinearity for axisymmetrically-polarized pulses in a uniaxial crystal is derived and the extended Stokes parameters (ESPs) based on cylindrical coordinates are newly-introduced. The simulation results by using this equation, providing the calculated ESPs, well explain our experimental observations: 1) the energy transfer is attributed to the four-wave-mixing effect, reflecting the overlapping between the axisymmetrically polarized modes, 2) the variations of the polarization defined from the ESPs are clarified to be affected by the self-and the cross-phase modulations, which make the effective propagation length long or short. (C) 2014 Optical Society of America

Nonlinear coupling between axisymmetrically-polarized ultrashort optical pulses in a uniaxial crystal
Masato Suzuki, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
OPTICS EXPRESS, 22, 14, 16903, 16915, OPTICAL SOC AMER, 2014年07月
英語, 研究論文（学術雑誌）, Nonlinear propagation of focused axisymmetrically-polarized ultrashort optical pulses along the optic axis in a uniaxial crystal is investigated experimentally and theoretically. The energy transfer between an azimuthally-polarized pulse and a radially-polarized pulse is observed. To analyze the nonlinear propagation, a general paraxial equation with a third-order nonlinearity for axisymmetrically-polarized pulses in a uniaxial crystal is derived and the extended Stokes parameters (ESPs) based on cylindrical coordinates are newly-introduced. The simulation results by using this equation, providing the calculated ESPs, well explain our experimental observations: 1) the energy transfer is attributed to the four-wave-mixing effect, reflecting the overlapping between the axisymmetrically polarized modes, 2) the variations of the polarization defined from the ESPs are clarified to be affected by the self-and the cross-phase modulations, which make the effective propagation length long or short. (C) 2014 Optical Society of America

Frequency-resolved measurement of the orbital angular momentum spectrum of femtosecond ultra-broadband optical-vortex pulses based on field reconstruction
Keisaku Yamane, Zhili Yang, Yasunori Toda, Ryuji Morita
NEW JOURNAL OF PHYSICS, 16, May, 053020 (WEB ONLY), IOP PUBLISHING LTD, 2014年05月
英語, 研究論文（学術雑誌）, We propose a high-precision method for measuring the orbital angular momentum (OAM) spectrum of ultra-broadband optical-vortex (OV) pulses from fork-like interferograms between OV pulses and a reference plane-wave pulse. It is based on spatial reconstruction of the electric fields of the pulses to be measured from the frequency-resolved interference pattern. Our method is demonstrated experimentally by obtaining the OAM spectra for different spectral components of the OV pulses, enabling us to characterize the frequency dispersion of the topological charge of the OAM spectrum by a simple experimental setup. Retrieval is carried out in quasi-real time, allowing us to investigate OAM spectra dynamically. Furthermore, we determine the relative phases (including the sign) of the topological-charge-resolved electric-field amplitudes, which are significant for evaluating OVs or OV pulses with arbitrarily superposed modes.

Generation of ultra-broadband pulses with axially-symmetric polarization based on coherent beam combining of optical vortices
Keisaku Yamane, Yasuyuki Shioda, Masato Suzuki, Yasunori Toda, Ryuji Morita
Optics InfoBase Conference Papers, Optical Society of America (OSA), 2014年
英語, 研究論文（国際会議プロシーディングス）, We demonstrated the generation of ultra-broadband optical pulses with axiallysymmetric polarization, on the basis of a coherent beam combining technique. The high polarization purity (~95 %) ranging from 750 to 880 nm was obtained. © 2014 Optical Society of America.

Spatiotemporal coherence of GaN excitons excited by an optical vortex with multiple orbital angular momentum
Kyohhei Shigematsu, Keisaku Yamane, Ryuji Morita, Yasunori Toda
Optics InfoBase Conference Papers, Optical Society of America (OSA), 2014年
英語, 研究論文（国際会議プロシーディングス）, The spatiotemporal coherence of excitons is investigated by degenerate four-wavemixing using optical vortices with multiple orbital angular momentum (OAM). The OAMresolved signal indicates that the topological phase with large OAM is robust against spatial decoherence. © 2014 OSA.

Over 1-mJ intense ultrashort optical-vortex pulse generation with programmable topological-charge control by chirped-pulse amplification
Keisaku Yamane, Asami Honda, Yasunori Toda, Ryuji Morita
Optics InfoBase Conference Papers, Optical Society of America (OSA), 2014年
英語, 研究論文（国際会議プロシーディングス）, We demonstrated the generation of over 1-mJ intense optical-vortex pulses of which topological charges were programmably controlled by computer-generated holograms. The pulse duration was characterized to be 27 fs by two-dimensional spectral shearing interferometry. © 2014 OSA.

Spatiotemporal coherence of GaN excitons excited by an optical vortex with multiple orbital angular momentum
Kyohhei Shigematsu, Keisaku Yamane, Ryuji Morita, Yasunori Toda
2014 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), IEEE, 2014年, ［査読有り］
英語, 研究論文（国際会議プロシーディングス）, The spatiotemporal coherence of excitons is investigated by degenerate four-wavemixing using optical vortices with multiple orbital angular momentum (OAM). The OAM-resolved signal indicates that the topological phase with large OAM is robust against spatial decoherence.

Generation of ultra-broadband pulses with axially-symmetric polarization based on coherent beam combining of optical vortices
Keisaku Yamane, Yasuyuki Shioda, Masato Suzuki, Yasunori Toda, Ryuji Morita
2014 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), IEEE, 2014年, ［査読有り］
英語, 研究論文（国際会議プロシーディングス）, We demonstrated the generation of ultra-broadband optical pulses with axially-symmetric polarization, on the basis of a coherent beam combining technique. The high polarization purity (similar to 95 %) ranging from 750 to 880 nm was obtained. (C) 2014 Optical Society of America

Ultrafast and ultra-broadband optical-vortex pulse generation and characterization
Ryuji Morita, Keisaku Yamane, Zhili Yang, Yasunori Toda
COMPLEX LIGHT AND OPTICAL FORCES VIII, 8999, SPIE-INT SOC OPTICAL ENGINEERING, 2014年
英語, 研究論文（国際会議プロシーディングス）, Subsequently to the previous generation of ultrashort and ultra-broadband optical-vortex (OV) pulses (pulse energy: several tens of mu J) in few-cycle regime, we demonstrate high-power OV pulse generation with topological charge flexibility by employing a 4-f OV converter and pre- and main-amplifications. Our configuration overcomes the low-throughput drawback of the vortex converter, simultaneously compensating for the angular dispersion. It also gives flexibility of OAM- or topological-charge control. Thus, we succeed in generation of mJ-class ultra-broadband OV pulses (similar to 790-similar to 820 nm) with a programmably-controlled topological charge. Moreover, we experimentally exhibit a high-precision method for measuring frequency-resolved OAM spectrum of femtosecond ultra-broadband OV pulses on the basis of electric-field reconstruction in the spatial domain. In addition, we present the generation of ultrashort pulses with axially-symmetric polarization by coherent beam combining of OVs.

Orbital Angular Momentum Spectral Dynamics of GaN Excitons Excited by Optical Vortices
Kyohhei Shigematsu, Yasunori Toda, Keisaku Yamane, Ryuji Morita
JAPANESE JOURNAL OF APPLIED PHYSICS, 52, 8, IOP PUBLISHING LTD, 2013年08月
英語, 研究論文（学術雑誌）, We report on the coherent dynamics of the photoexcited orbital angular momentum (OAM) states of GaN excitons. The measurements were performed by a pump-probe four-wave mixing (FWM) using optical vortex (OV) pulses, where the pump OV pulse transfers its OAM to the center of mass momentum of excitons and the conversion of OAM via FWM with the probe pulse is detected. Especially, we performed analysis of the signal using an OAM-resolved spectroscopy, which allows us to evaluate the dephasing dynamics of excitons in time and space. The results indicate that near perfect conversion is achieved using the OV pulses with nonzero OAM and its spatial coherence remains high during the dephasing time, clearly indicating that the excitons keep the OAM transferred by the pump OV. In contrast, the component associated with the imperfect conversion becomes significant when one of the incident pulses intentionally includes an OAM-free component. The effect is clearly confirmed by the FWM excited by the pump with multiple OAM. (C) 2013 The Japan Society of Applied Physics

Nonlinear Coupling Between Radially- And Azimuthally-Polarized Modes of Ultrashort Optical Pulses in an Anisotropic Crystal
Masato Suzuki, Keisaku Yamane, Yasunori Toda, Ryuji Morita
2013 CONFERENCE ON LASERS AND ELECTRO-OPTICS PACIFIC RIM (CLEO-PR), IEEE, 2013年, ［査読有り］
英語, 研究論文（国際会議プロシーディングス）, We investigate nonlinear propagation of ultrashort optical pulses with radially- and azimuthally-polarized modes in a uniaxial crystal. The energy exchange between the modes, ascribed to nonlinear four-wave-mixing effect with Gouy-phase shifts, is discussed.

Nonlinear Conversion between Ultrashort Radially- and Azimuthally-Polarized Pulses in an Anisotropic Media
Masato Suzuki, Keisaku Yamane, Yasunori Toda, Ryuji Morita
2013 CONFERENCE ON LASERS AND ELECTRO-OPTICS EUROPE AND INTERNATIONAL QUANTUM ELECTRONICS CONFERENCE (CLEO EUROPE/IQEC), IEEE, 2013年, ［査読有り］
英語, 研究論文（国際会議プロシーディングス）

Programmable Ultrashort Optical-vortex Pulse Generation Using Optical Parametric Amplification and 4-f Configuration
Keisaku Yamane, Asami Honda, Kyohhei Shigematsu, Yasunori Toda, Ryuji Morita
2013 CONFERENCE ON LASERS AND ELECTRO-OPTICS PACIFIC RIM (CLEO-PR), IEEE, 2013年, ［査読有り］
英語, 研究論文（国際会議プロシーディングス）, We demonstrate the optical parametric amplification of optical-vortex pulses with the programmable topological-charge control. Combination of optical-parametric amplification and 4-f configuration overcomes the low-throughput drawback of the vortex converter, simultaneously compensating for the angular dispersion.

Frequency-resolved Orbital Angular Momentum Spectrum Measurement of Ultra-broadband Optical Vortices
Zhili Yang, Keisaku Yamane, Yasunori Toda, Ryuji Morita
2013 CONFERENCE ON LASERS AND ELECTRO-OPTICS PACIFIC RIM (CLEO-PR), IEEE, 2013年, ［査読有り］
英語, 研究論文（国際会議プロシーディングス）, We experimentally exhibit a high-precision method for measuring frequency-resolved orbital angular momentum (OAM) spectrum of femtosecond ultra-broadband optical-vortex pulses from fork-like interferograms. This method enables us to evaluate topological-charge dispersion of ultra-broadband optical-vortex pulses.

Quasi-real-time Measurement of Orbital Angular Momentum Spectra of Ultra-broadband Optical Vortices from Fork-like Interferograms
Zhili Yang, Keisaku Yamane, Yasunori Toda, Ryuji Morita
2013 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), IEEE, 2013年, ［査読有り］
英語, 研究論文（国際会議プロシーディングス）, We experimentally demonstrate a simple and high-precision method for measuring orbital angular momentum (OAM) spectra of femtosecond ultra-broadband optical-vortex pulses from fork-like interferograms. This method enables quasi-real-time OAM measurement for ultra-short or ultra-broadband optical vortices.

Amplification of ultrashort optical-vortex pulses with programmable topological-charge control
Keisaku Yamane, Yasunori Toda, Ryuji Morita
2013 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), IEEE, 2013年, ［査読有り］
英語, 研究論文（国際会議プロシーディングス）, We demonstrate the amplification of ultrashort optical-vortex pulses through the optical parametric process, where optical-vortex seed pulses with computer-controlled topological charges are employed. In this scheme, the low-throughput drawback of the vortex converter is overcome. (C) 2013 Optical Society of America

Efficient Laguerre-Gaussian mode conversion for orbital angular momentum resolved spectroscopy
Y. Toda, K. Shigematsu, K. Yamane, R. Morita
Optics Communications, 308, 147, 151, 2013年
英語, 研究論文（学術雑誌）, The orbital angular momentum (OAM) resolved spectroscopy is being applied to various research fields associated with optical vortices or Laguerre-Gaussian (LG) beams, in which the key technique is to convert LG beams to a fundamental Gaussian (HG≡HG00) beam. In this work, we propose a method to realize efficient mode conversion by using spiral phase modulations. Numerical simulations and experiments are carried out to compare our proposal with the standard technique using rotational phase modulations. The results reveal that our proposed method improves the uniformity of the conversion efficiency across various OAM, allowing us to obtain precise OAM spectra. © 2013 Elsevier B.V.

Ultrashort optical-vortex pulse generation in few-cycle regime
Keisaku Yamane, Yasunori Toda, Ryuji Morita
OPTICS EXPRESS, 20, 17, 18986, 18993, OPTICAL SOC AMER, 2012年08月, ［査読有り］
英語, 研究論文（学術雑誌）, We generated a 2.3-cycle, 5.9-fs, 56-mu J ultrashort optical-vortex pulse (ranging from similar to 650 to similar to 950 nm) in few-cycle regime, by optical parametric amplification. It was performed even by using passive elements (a pair of prisms and chirped mirrors) for chirp compensation. Spectrally-resolved interferograms and intensity profiles showed that the obtained pulses have no spatial or topological-charge dispersion during the amplification process. To the best of our knowledge, it is the first generation of optical-vortex pulses in few-cycle regime. They can be powerful tools for ultrabroadband and/or ultrafast spectroscopy and experiments of high-intensity field physics. (C) 2012 Optical Society of America

Femtosecond photoisomerization of azobenzene-derivative binding to DNA
Tao Chen, Kazumasa Igarashi, Naoya Nakagawa, Keisaku Yamane, Taiga Fujii, Hiroyuki Asanuma, Mikio Yamashita
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY, 223, 2-3, 119, 123, ELSEVIER SCIENCE SA, 2011年09月
英語, 研究論文（学術雑誌）, Ultrafast photoisomerization and relaxation dynamics of trans (T) 4'-methylthioazobenzene (AzD) binding to double-strand DNA (T-AzD-dsDNA) as well as single-strand DNA (T-AzD-ssDNA) and T-AzD were investigated by the measurement of femtosecond absorbance changes on S-2(T) excitation (400 nm) with the rate equation analysis. All the solutions showed the fast (tau(1), A(1)) and slow (tau(2), A(2)) decay components and the offset component (A(3)). The greatly different negative or positive absorbance change behaviors by the probe wavelength of 400 or 420 nm for the T-AzD solution were attributed to the remarkable dependence of the absorption cross-section difference between the T-isomer excited and ground states on the probe wavelength and of that between the cis (C)- and T-isomer ground states. The significantly shorter S-2(T) state lifetimes tau(1) for T-AzD-dsDNA and T-AzD-ssDNA were observed to be 30 and 60 fs, respectively, compared with that (220 fs) of T-AzD. This is presumably attributed to the intramolecular electron transfer from DNA bases to T-AzD in T-AzD-DNAs. suggesting the first observation of electron transfer in an ultrafast photoisomerization system interacting with DNA. While, the kinetic rate k(2.1)(T.I) from the S-2(T) state to the bottleneck intermediate state I-1(T.C) of the initial process in the T to C photoisomerization and the I-1(T.C) state lifetime tau(2) hardly changed like 1.3 x 10(11). 1.4 x 10(11) and 1.6 x 10(11)s(-1) and like 6.7, 6.2 and 6.0 Ps, respectively. The latter implies that the birth time of the C-isomer is almost the same for all the solutions. Furthermore, the T-to-C photoisomerization rate eta(T,C) by single-shot excitation was determined from A(3) to be 1.2%, 0.36% and 0.22% at the 100-nJ pulse energy level, indicating that the T-AzD molecule is one of the most efficient T-to-C photoisomerization molecules. The decrease of eta(T,C) in T-AzD-DNAs is due to the dramatic shortening of the excited-state lifetime tau(1). (C) 2011 Elsevier B.V. All rights reserved.

Spectral Phase Characterization of Two-Octave Bandwidth Pulses by Two-Dimensional Spectral Shearing Interferometry Based on Noncollinear Phase Matching With External Pulse Pair
Keisaku Yamane, Masato Katayose, Mikio Yamashita
IEEE PHOTONICS TECHNOLOGY LETTERS, 23, 16, 1130, 1132, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2011年08月
英語, 研究論文（学術雑誌）, Noncollinear phase matching with an external powerful reference pulse pair and an extremely broadband pulse to be measured in two-dimensional spectral shearing interferometry enabled us to characterize its spectral phase over the so-far broadest wavelength range from 328 to 1363 nm. The method has the additional advantage of the shorter measurement time (10 s) and higher sensitivity (at least 100 times) compared to conventional modified spectral-phase interferometry for direct electric-field reconstruction. This result exceeding two octaves suggests a possibility of the first generation of a single subcycle pulse in the ultraviolet to near-infrared region by the application to the feedback chirp compensation of the induced phase-modulated pulse with the use of a recently developed spatial light modulator with an over-two-octave bandwidth.

Optical Parametric Amplifier Pumped at 266 nm toward Ultrashort Near-Ultraviolet Gigawatt Pulses
Takashi Tanigawa, Keisaku Yamane, Naoki Karasawa, Mikio Yamashita
JAPANESE JOURNAL OF APPLIED PHYSICS, 50, 7, JAPAN SOC APPLIED PHYSICS, 2011年07月
英語, 研究論文（学術雑誌）, Near-ultraviolet (UV) broadband (370-470 nm) amplification up to 2.4 mu J energy from a single-pass beta-barium borate (BBO) crystal is demonstrated by noncollinear optical parametric amplification (NOPA) pumped by the third harmonic (TH, 40 mu J pump energy) of Ti:sapphire laser pulses at 1 kHz repetition rate. The result of simulation with the pump depletion effect due to two-photon absorption (TPA) shows an excellent agreement with the experimental demonstration. Further simulation suggests that the intense pump (energy of 1 mJ) is useful, in spite of the increase in TPA, for obtaining high-energy amplification of 47 mu J for several femtosecond near-UV pulses with 4.7% efficiency using a commercially available high-power femtosecond laser system. (C) 2011 The Japan Society of Applied Physics

Frequency-Varying Spectral Shear Interferometry for Characterization of Extremely Short Attosecond Pulses
Jiangfeng Zhu, Shaobo Fang, Keisaku Yamane, Mikio Yamashita
IEEE JOURNAL OF QUANTUM ELECTRONICS, 47, 6, 810, 818, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2011年06月
英語, 研究論文（学術雑誌）, We theoretically investigate the complete amplitude and phase characterization of the isolated attosecond extreme ultraviolet (XUV) electric field by the spectral phase interferometry technique. Spectral shear needed for reconstruction of the spectral phase of the XUV pulse is prepared by modulating the driving optical pulse into two with different central wavelengths. We find that the spectral shear between the XUV pulses is almost linearly variable with the frequency, thus the phase reconstruction algorithm is modified by a non-uniformly sampled step concatenation. Numerical simulation using the harmonic spectrum and phase obtained from the saddle point analysis based on the widely used Lewenstein model indicates that this novel method is capable of measuring extremely short attosecond XUV pulses with several advantages owing to the all-optical apparatus: high efficiency and high time resolution, possibility of single-shot measurement, which provides a beneficial improvement to the current complicated photoelectron spectroscopic technique. We suggest that such a method is easy to implement, and propose a feasible experimental arrangement.

Generation of Sub-900-μJ Supercontinuum With a Two-Octave Bandwidth Based on Induced Phase Modulation in Argon-Filled Hollow Fiber
Fang Shaobo, Yamane Keisaku, Zhu Jiangfeng, Zhou Chun, Zhang Zhigang, Yamashita Mikio
IEEE Photonics Technology Letters, 23, 11, 688, 690, IEEE, 2011年06月
英語, 研究論文（学術雑誌）, We succeeded in generating 860-μJ pulses spanning the range from 270 to 1000 nm, the highest energy two-octave pulses demonstrated to date, by utilizing not only self-phase modulation but also induced phase modulation based on nonlinear co-propagation of fundamental and second-harmonic femtosecond pulses in a pressure gradient Ar-gas-filled hollow fiber. This corresponds to 1.5-fs, 0.3-TW, 0.65-cycle transform-limited pulses at a 1-kHz repetition rate, which serves as an optical source for ultrafast ultrabroadband spectroscopy and quantum control as well as attosecond science and technology.

Sub-1mJ Over-Two-Octave White-Light Continuum Generated by Induced Phase Modulation in Argon-Filled Hollow Fiber
Shaobo Fang, Keisaku Yamane, Jiangfeng Zhu, Chun Zhou, Zhigang Zhang, Mikio Yamashita
2011 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), IEEE, 2011年, ［査読有り］
英語, 研究論文（国際会議プロシーディングス）, We generated 0.9-mJ pulses spanning from 270 to 1200 nm by utilizing the induced phase modulation in pressure gradient hollow fiber. This enables 1.5-fs, 0.65-cycles, 0.6-TW, 1-kHz transform-limited pulses for attosecond science and technology.

Ultrabroadband spectral amplitude modulation using a liquid crystal spatial light modulator with ultraviolet-to-near-infrared bandwidth.
Zhu J, Tanigawa T, Chen T, Fang S, Yamane K, Sekikawa T, Yamashita M
Applied optics, 49, 3, 350, 357, 3, 2010年01月, ［査読有り］

The development of angularly-dispersed non-collinear optical parametric amplifier for generation of high power optical pulses in monocycle regime
Keisaku Yamane, Takashi Tanigawa, Taro Sekikawa, Mikio Yamashita
Optics InfoBase Conference Papers, Optical Society of America (OSA), 2010年
英語, 研究論文（国際会議プロシーディングス）, We greatly improved our angularly-dispersed NOPA system and introduced a new stretcher for seed pulses. Consequently, we achieved the broadest gain bandwidth ranging from 500 to 1030 nm with output pulse energy of 45 μJ. © OSA / UP 2010.

Ultrabroadband spectral amplitude modulation using a liquid crystal spatial light modulator with ultraviolet-to-near-infrared bandwidth
Jiangfeng Zhu, Takashi Tanigawa, Tao Chen, Shaobo Fang, Keisaku Yamane, Taro Sekikawa, Mikio Yamashita
APPLIED OPTICS, 49, 3, 350, 357, OPTICAL SOC AMER, 2010年01月, ［査読有り］
英語, 研究論文（学術雑誌）, The first demonstration to our knowledge in the spectral range from 300 to 1100 nm is presented for the amplitude modulation characteristics of a two-channel 648-pixel liquid crystal spatial light modulator. The broadest spectral amplitude modulation for UV (380-420 nm) and visible-to-near-IR (500-900 nm) pulses to generate a spectral-shifted pulse pair is experimentally realized. The results show that the liquid crystal spatial light modulator has a potential application for attosecond extreme-UV pulse characterization with the conventional SPIDER algorithm and the capability to shape monocycle optical pulses. (C) 2010 Optical Society of America

Ultra-Broadband Spectral-Shifted Pulse Pair Generation by Amplitude Modulation for Single Attosecond Pulse Characterization Using the SPIDER Method
J. Zhu, T. Tanigawa, T. Chen, S. Fang, K. Yamane, M. Yamashita
2010 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO) AND QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE (QELS), IEEE, 2010年, ［査読有り］
英語, 研究論文（国際会議プロシーディングス）, Ultra-broadband amplitude modulation for spectral-shifted pulse pair generation is realized by a liquid-crystal spatial light modulator. The results indicate that it's a promising way for single attosecond pulse characterization by the conventional SPIDER method. (C) 2010 Optical Society of America

Monocycle pulse generation and octave bandwidth amplification
Keisaku Yamane, Takashi Tanigawa, Taro Sekikawa, Mikio Yamashita
2009 LASERS & ELECTRO-OPTICS & THE PACIFIC RIM CONFERENCE ON LASERS AND ELECTRO-OPTICS, VOLS 1 AND 2, 421, +, IEEE, 2009年, ［査読有り］
英語, 研究論文（国際会議プロシーディングス）, We demonstrated experimentally the generation of 65-mu J, 5 8-fs optical pulses with an ultrabroad bandwidth (540 - 1000 nm) by the use of a double-pass angularly-dispersed noncollinear optical parametric amplifier

Noncollinear Optical Parametric Amplification Pumped by the Third Harmonics of a Ti:sapphire Laser
Takashi Tanigawa, Keisaku Yamane, Taro Sekikawa, Mikio Yamashita
ULTRAFAST PHENOMENA XVI, 92, 759, +, SPRINGER-VERLAG BERLIN, 2009年, ［査読有り］
英語, 研究論文（国際会議プロシーディングス）, Broardband amplification in the 380-490 nm region was achieved by ultraviolet (UV) pumped noncollinear optical parametric amplification. This result leads to 6 fs UV pulse generation and can be utilized to amplify monocycle pulses.

Angularly-dispersed optical parametric amplification of optical pulses with one-octave bandwidth toward monocycle regime
K. Yamane, T. Tanigawa, T. Sekikawa, M. Yamashita
OPTICS EXPRESS, 16, 22, 18345, 18353, OPTICAL SOC AMER, 2008年10月
英語, 研究論文（学術雑誌）, We demonstrated experimentally the generation of 65-mu J, 5.8-fs optical pulses with an ultrabroad bandwidth (540 - 1000 nm) by the use of a double-pass angularly-dispersed non-collinear optical parametric amplifier. We also confirmed up to the 95-mu J output from the amplifier when seed pulses were not pre-compensated for. Furthermore, we confirmed that the broadband pump pulses brought in the broader gain bandwidth (from 520 to 1080 nm) than numerical estimation based on CW-pump approximation. To the best of our knowledge, this is the system with the broadest gain bandwidth. (C) 2008 Optical Society of America

Nearly-octave broadband, high-powered optical parametric amplification toward monocycle regime
Keisaku Yamane, Takashi Tanigawa, Taro Sekikawa, Mikio Yamashita
2008 CONFERENCE ON LASERS AND ELECTRO-OPTICS & QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE, VOLS 1-9, 1381, +, IEEE, 2008年, ［査読有り］
英語, 研究論文（国際会議プロシーディングス）, We demonstrated the generation of 34-mu J, 14-fs optical pulses with an ultrabroad bandwidth (540 - 1000 nm) by the use of one angularly-dispersed non-collinear optical parametric amplifier. (C) 2007 Optical Society of America

モノサイクル域光パルス圧縮
山下 幹雄, 山根 啓作, 森田 隆二
應用物理, 76, 2, 154, 159, 応用物理学会, 2007年02月10日
日本語

キャリヤーエンベロープ位相安定化モノサイクル光の発生
山根 啓作, 山下 幹雄
光学, 36, 2, 88, 90, 応用物理学会分科会日本光学会, 2007年02月10日
日本語

Generation of sub-3-fs optical pulses using induced phase modulation in an Ar-gas-filled hollow fiber
Eiichi Matsubara, Keisaku Yamane, Toshiyuki Naoi, Toshihiko Kito, Eisuke Haraguchi, Taro Sekikawa, Mikio Yamashita
ULTRAFAST PHENOMENA XV, 88, 113, +, SPRINGER-VERLAG BERLIN, 2007年, ［査読有り］
英語, 研究論文（国際会議プロシーディングス）, We demonstrate the first pulse compression of ultrabroadband white-light continuum generated using both induced- and self-phase modulations in an Ar-gas-filled hollow fiber. By feedback chirp compensation with a liquid crystal spatial light modulator and a modified spectral interferometry for direct electric-field reconstruction, 2.6-fs, 1.4-GW, 1.3-cycle transform-limited pulses are generated in the visible to near-infrared region.

Optical parametric amplification of optical pulses with a nearly one-octave bandwidth from a hollow fiber
K. Yamane, A. Iwasaki, T. Tanigawa, T. Sekikawa, M. Yamashita
2007 CONFERENCE ON LASERS & ELECTRO-OPTICS/QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE (CLEO/QELS 2007), VOLS 1-5, 2418, +, IEEE, 2007年, ［査読有り］
英語, 研究論文（国際会議プロシーディングス）, We developed an angularly dispersed noncollinear optical parametric amplifier with a 300-THz bandwidth (550 - 1000 nm) for the first time. To the best of our knowledge, this is the broadest parametric gain. (C) 2006 Optical Society of America

Efficient compression of carrier-envelope phase-locked laser pulses to 5 A using an aluminum-coated hollow fiber
Eisuke Haraguchi, Takashi Tanigawa, Eiichi Matsubara, Keisaku Yamane, Mikio Yamashita, Taro Sekikawa
2007 CONFERENCE ON LASERS & ELECTRO-OPTICS/QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE (CLEO/QELS 2007), VOLS 1-5, 1347, 1348, IEEE, 2007年, ［査読有り］
英語, 研究論文（国際会議プロシーディングス）, Carrier-envelope phase-lacked 0.13-TW, 5.2-fs laser pulses were generated by using a 56-cm-long aluminum-coated hollow fiber with an efficiency of 66 %, improved by coating aluminum inside the fiber with a core diameter of 500-mu m. (C) 2007 Optical Society of America

Generation of 2.6 fs optical pulses using induced-phase modulation in a gas-filled hollow fiber
Eiichi Matsubara, Keisaku Yamane, Taro Sekikawa, Mikio Yamashita
Journal of the Optical Society of America B: Optical Physics, 24, 4, 985, 989, Optical Society of American (OSA), 2007年
英語, 研究論文（学術雑誌）, We report quasi-one-optical-cycle pulse compression of the ultrabroadband white-light continuum generated using both induced-phase modulation (IPM) and self-phase modulation (SPM) in a 3.0 atom Ar-gas-filled hollow fiber. Fundamental and second harmonic waves of amplified 30 fs Ti:sapphire laser pulses were irradiated into a 37 cm hollow fiber with an inner diameter of 140 μm. When the two pulses were temporally overlapped in the hollow fiber, the white-light continuum with the wavelength range of 350-1050 nm was generated. The spectral phase of the white-light continuum was measured by a modified spectral interferometry for direct electric-field reconstruction, and quasi-automatic feedback chirp compensation was carried out using a programmable liquid-crystal spatial light modulator placed on the Fourier plane of a 4-f system. As a result, 2.6 fs, 3.6 μJ, 1.3 cycle transform-limited (TL) pulses with a peak power up to 1.4 GW at a 1 kHz repetition rate were generated in the visible to near-infrared region (the over-one-octave bandwidth of 450-975 nm). The fact that the IPM + SPM light was compressed to the TL duration is important toward the generation of a single, intense one-optical-cycle pulse in the visible region. © 2007 Optical Society of America.

Quasi-automatic phase-control technique for chirp compensation of pulses with over-one-octave bandwidth - Generation of few- to mono-cycle optical pulses
Mikio Yamashita, Keisaku Yamane, Ryuji Morita
IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS, 12, 2, 213, 222, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2006年03月
英語, 研究論文（学術雑誌）, This paper introduces our self-recognition type of the computer-controlled spectral phase, compensator (SRCSC), which consists of a greatly accurate phase manipulator with a spatial light modulator (SLM), a highly sensitive phase characterizer using a modified spectral phase interferometry for direct electric field reconstruction (M-SPIDER), and a computer for phase analysis and SLM control operating in the immediate feedback (FB) mode. The application of the SRCSC to adaptive compensation of various kinds of complicated spectral phases such as nonlinear chirped pulses with a weak intensity, induced-phase modulated pulses, photonic-crystal-fiber (PCF) output pulses, and nonlinear chirped pulses exceeding a 500-rad phase variation over-one-octave bandwidth demonstrated that the SRCSC is significantly useful for compensation of arbitrary nonlinear chirp and hence enables us to generate quasi-monocycle transform-limited (TL) pulses with a 2.8-fs duration. To the best of our knowledge, this 1.5-cycle pulse is the shortest single pulse with a clean temporal profile in the visible to near-infrared region.

Generation of carrier-envelop-phase stabilized 3.3-fs optical pulses
K. Yamane, T. Naoi, A. Suguro, R. Morita, M. Yamashita, K. Sugiyama, M. Kitano
Conference on Lasers and Electro-Optics Europe - Technical Digest, 384, Institute of Electrical and Electronics Engineers Inc., 2005年
英語, 研究論文（国際会議プロシーディングス）

Comparison between photonic crystal fiber and tapered fiber for pulse compression - Toward mono-cycle optical pulses　　　　　　　　　　　　　　　
Muneyuki Adachi, Keisaku Yamane, Ryuji Morita, Mikio Yamashita
Quantum Electronics and Laser Science Conference (QELS), 3, 1630, 1632, 2005年
英語, 研究論文（国際会議プロシーディングス）, A feedback system that combined modified-SPIDER and 4-f active-chirp compensation enabled us to compress photonic-crystal-fiber and tapered-fiber outputs to 5.8 and 8.4 fs, respectively. Advantages and problems of both fibers for further pulse compression were mentioned. © 2005 Optical Society of America.

Few-cycle pulse compression using microstructured fibers
Muneyuki Adachi, Keisaku Yamane, Ryuji Marita, Mikio Yamashita
Conference on Lasers and Electro-Optics Europe - Technical Digest, 2005年, ［査読有り］
英語, 研究論文（国際会議プロシーディングス）

Nonlinear optical phenomena in gas-filled or microstructured fibers for few- to mono-cycle pulses
R. Morita, K. Yamane, M. Adachi, M. Yamashita
IQEC, International Quantum Electronics Conference Proceedings, 2005, 544, 545, 2005年, ［査読有り］
英語, 研究論文（国際会議プロシーディングス）, Nonlinear optical phenomena dominating spectral broadening and spectral phase behavior of pulses propagated in gas-filled or microstructure fibers for compression up to few- to mono-cycle region were discussed from the standpoint of time-frequency characteristics.

Microstructured fiber feedback pulse compression to few optical cycles
M Adachi, K Yamane, R Morita, M Yamashita
ULTRAFAST PHENOMENA XIV, 79, 49, 51, SPRINGER-VERLAG BERLIN, 2005年, ［査読有り］
英語, 研究論文（国際会議プロシーディングス）, A feedback system that combined modified-SPIDER and 4-f active-chirp compensation enabled us to compress photonic-crystal-fiber and tapered-fiber outputs to 6.6 and 8.4 fs, respectively. Compressed-pulse results well agree with fringe-resolved autocorrelation measurement ones.

Sub-5-fs pulse compression of laser output using photonic crystal fiber with short zero-dispersion wavelength
M Adachi, K Yamane, R Morita, M Yamashita
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS, 44, 46-49, L1423, L1425, INST PURE APPLIED PHYSICS, 2005年
英語, 研究論文（学術雑誌）, Output pulses from a photonic crystal fiber (PCF) with a zero-dispersion wavelength (ZDW: 853 nm) were compressed to 5.8 fs by feedback spectral-phase compensation. Furthermore, for another PCF with a shorter ZDW (744 nm), whose output spectral-phase measurement and pulse compression are generally thought to be difficult because of coherence degradation between pulses, we measured successfully their phases in the entire spectral region (480 to 1000 nm) by a suitable selection of input pulse and fiber parameters. The pulse compression experiment using an improved feedback system showed that in the short-wavelength region, pulses can be compressed to 4.9 fs, whereas in the entire spectral region, pulses cannot be compressed. This is because the visibility of the spectral interferogram in the spectral-phase interferometry for direct electric-field reconstruction (SPIDER) signal in the longer-wavelength region corresponding to the phase-sensitive soliton-breaking-up region is degraded by large phase modulation using a spatial light modulator.

Wavelet-transform analysis of spectral shearing interferometry for phase reconstruction of femtosecond optical pulses
Yuqiang Deng, Zubin Wu, Lu Chai, Ching-Yue Wang, Keisaku Yamane, Ryoji Morita, Mikio Yamashita, Zhigang Zhang
Optics Express, 13, 6, 2120, 2126, Optical Society of American (OSA), 2005年
英語, 研究論文（学術雑誌）, We introduce a novel method for retrieving the phase from a spectral shearing interferogram, based on wavelet-transform technique. We demonstrate with both theoretical and experimental data that this technique provides an alternative and reliable technique for phase retrieval, particularly for highly structured pulse spectra. © 2005 Optical Society of America.

2.8-fs clean single transform-limited optical-pulse generation and characterization
K Yamane, T Kito, R Morita, M Yamashita
ULTRAFAST PHENOMENA XIV, 79, 13, 15, SPRINGER-VERLAG BERLIN, 2005年
英語, 研究論文（国際会議プロシーディングス）, We compensated for chirp of ultrabroad-band pulses with an over-one-octave bandwidth (460 - 1060 nm) using a feedback method. Consequently, 2.8-fs, 1.5-cycle transform-limited pulses were generated.

Pulse compression using direct feedback of the spectral phase from photonic crystal fiber output without the need for the Taylor expansion method
M Adachi, K Yamane, R Morita, M Yamashita
IEEE PHOTONICS TECHNOLOGY LETTERS, 16, 8, 1951, 1953, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2004年08月
英語, 研究論文（学術雑誌）, Characterization and compensation of the complex spectral phase and the temporal profile of output pulses from a photonic crystal fiber (620-945-nm spectral broadening) were performed using a computer-controlled feedback system that combines a modified spectral-phase interferometry for direct electric-field reconstruction apparatus and only a 4-f chirp compensator having a spatial light modulator. These pulses were adaptively compressed from 12-fs input pulses to 6.8-fs. In addition, the compressed pulse profile showed excellent agreement with results measured independently with fringe-resolved auto-correlation.

Generation and characterization of 3.4-fs optical pulses with over-one-octave bandwidth
K Yamane, ZG Zhang, A Suguro, K Oka, R Morita, M Yamashita
ULTRAFAST OPTICS IV, 95, 97, 102, SPRINGER, 2004年, ［査読有り］
英語, 研究論文（国際会議プロシーディングス）, We feedback-compensated for chirp of optical pulses with over one-octave bandwidth (495-1090 nm) generated by self-phase modulation in a single-argon-filled hollow fiber, and generated 3.4-fs, 1.56 optical-cycle pulses.

Analysis of compressed 3.4 fs-optical pulse based on deviation from its Fourier-transform-limited pulse using Wigner distribution function
Ryuji Morita, Keisaku Yamane, Mikio Yamashita
OSA Trends in Optics and Photonics Series, 96 A, 793, 795, 2004年01月01日
Time-frequency analysis of monocycle-region optical pulses was performed using the Wigner distribution function. The difference between the normalized Wigner distribution functions for a measured pulse and its Fourier-transform-limited pulse provides detailed information of their deviations. © 2003 Optical Society of America.

Adaptive pulse compression for photonic crystal fiber by direct feedback of spectral phase
Muneyuki Adachi, Keisaku Yamane, Ryuji Morita, Mikio Yamashita
OSA Trends in Optics and Photonics Series, 96 A, 783, 785, 2004年01月01日
A computer-contralled feedback system that combined modified-SPIDER and a 4-f active chirp compensator enabled us to compress photonic-crystal-fiber output pulses to 6.8 fs. Furthermore, the compressed-pulse profile showed the excellent agreement with fringe-resolved autocorrelation measurement. © 2003 Optical Society of America.

Experimental and theoretical demonstration of validity and limitations in fringe-resolved autocorrelation measurements for pulses of few optical cycles
K. Yamane, T. Kito, R. Morita, M. Yamashita
Optics Express, 12, 12, 2762, 2773, Optical Society of American (OSA), 2004年
英語, 研究論文（学術雑誌）, Using 3.6- and 5.3-fs pulses, we demonstrated theoretically and experimentally that fringe-resolved autocorrelation (FRAC) traces are distorted by bandwidth limitations of the second-harmonic generation (SHG) in 10-μm-thick, type I β-BaB2O4 for pulses shorter than sub-5 fs. In addition, detailed numerical analysis of the SHG showed that the optimum crystal angle where the FRAC trace distortion becomes minimum is in disagreement not only with the phase-matching angle but also with the angle where the FRAC signal intensity becomes maximum. Furthermore, the apparent pulse duration measured at a nonoptimum angle was confirmed to become shorter than that of its transform-limited pulse, in excellent agreement with the calculated result. © 2004 Optical Society of America.

Optical pulse compression to 3.4 fs in the monocycle region by feedback phase compensation
K Yamane, ZG Zhang, K Oka, R Morita, M Yamashita, A Suguro
OPTICS LETTERS, 28, 22, 2258, 2260, OPTICAL SOC AMER, 2003年11月, ［査読有り］
英語, 研究論文（学術雑誌）, We, compensated for chirp of optical pulses with an over-one-octave bandwidth (495,71090 run; center wavelength of 655.4 nm) produced by self-phase modulation in a single argon-filled hollow fiber and generated 3.4-fs, 1.56 optical-cycle pulses ( 00 nJ, 1-kHz repetition rate). This was achieved with a feedback system combined with only one 4-f phase compensator with a spatial light modulator and a significantly improved phase characterizer based on modified spectral phase interferometry for direct electric-field reconstruction. To the best of our knowledge, this is the shortest pulse in the visible-to-infrared region. (C) 2003 Optical Society of America.

Sub-4 fs optical-pulse generation using a feedback chirp-compensation method　　　　　　　　　　　　　　　
Keisaku Yamane, Zhigang Zhang, Akira Suguro, Ryuji Morita, Mikio Yamashita
OSA Trends in Optics and Photonics Series, 88, 1582, 1584, Optical Society of American (OSA), 2003年
英語, 研究論文（国際会議プロシーディングス）, We compensated for chirp of ultrabroad-band pulses with over-one-octave bandwidth using a feedback method. Consequently, we found the duration of compensated pulses is 4.0 fs. Furthermore, the generation of 3.6-fs pulses with sub-pulses was confirmed. © 2002 Optical Society of America.

Characterization of 3.4-fs optical pulses generated in the monocycle region　　　　　　　　　　　　　　　
Keisaku Yamane, Zhigang Zhang, Akira Suguro, Ryuji Morita, Mikio Yamashita
OSA Trends in Optics and Photonics Series, 88, 2091, 2093, Optical Society of American (OSA), 2003年
英語, 研究論文（国際会議プロシーディングス）, We have characterized ultrabroad-band optical pulses with over-one-octave bandwidth (495 - 1090 nm) by use of an improved modifled-SPIDER apparatus and compressed the pulses to 3.4-fs (1.56 cycles) by a feedback phase compensation. © 2003 Optical Society of America.

Time-frequency analysis of sub-4 fs optical pulses with over-one-octave bandwidth using Wigner distribution function
Ryuji Morita, Hayato Takenaka, Keisaku Yamane, Mikio Yamashita
Conference on Lasers and Electro-Optics Europe - Technical Digest, 455, 2003年, ［査読有り］
英語, 研究論文（国際会議プロシーディングス）, In this paper, we analyze temporal and spectral properties of sub-4 fs optical pulses with over-one-octave bandwidth using Wigner distribution function (WDF). The analytic results suggested that WDF enables us to intuitively and usefully obtain more information about the deviation from the perfect Fourier transform limited FTL pulse than other representations for monocycle-like pulse generation. © 2003 IEEE.

Sub-5 fs optical pulse characterization
R Morita, M Hirasawa, N Karasawa, S Kusaka, N Nakagawa, K Yamane, LM Li, A Suguro, M Yamashita
MEASUREMENT SCIENCE AND TECHNOLOGY, 13, 11, 1710, 1720, IOP PUBLISHING LTD, 2002年11月
英語, 研究論文（学術雑誌）, Ultrabroadband optical pulses generated through self-phase and induced-phase modulation effects and ultrashort optical pulses whose phases were compensated for using a 4f pulse shaper with a spatial phase modulator were generated. Interferometric autocorrelation, frequency-resolved optical gating and spectral phase interferometry for direct electric-field reconstruction (SPIDER) measurements were made to characterize these pulses, and the results were compared. The generation of 5.0 fs (2.4 cycle) or shorter optical pulses was confirmed. For much shorter pulses, below-two-cycle or monocycle optical pulses, single-shot characterization excluding the errors due to the pulse-to-pulse fluctuation is essential. The sensitivity of SPIDER, which is the most advantageous characterization technique apart from its low sensitivity, was improved by a factor of about a hundred (similar to 1 nJ/THz-bandwidth). Instead of a chirped reference pulse split from the pulse to be characterized, a powerful external pulse from a Ti:sapphire laser amplifier as a highly intensive chirped pulse was employed. By use of this modified SPIDER, the characterization of an over-one-octave ultrabroadband optical pulse was performed. This modified-SPIDER method is the most promising for characterization of monocycle optical pulses.

Absorption-free optical control of spin systems: The quantum Zeno effect in optical pumping
T Nakanishi, K Yamane, M Kitano
PHYSICAL REVIEW A, 65, 1, AMER PHYSICAL SOC, 2002年01月
英語, 研究論文（学術雑誌）, We show that atomic spin motion can be controlled by circularly polarized light without light absorption in the strong pumping limit. In this limit, the pumping light, which drives the empty spin state, destroys the Zeeman coherence effectively and freezes the coherent transition via the quantum Zeno effect. It is verified experimentally that the amount of light absorption decreases asymptotically to zero as the incident light intensity is increased.

A study on novel spectral behaviors of ultrabroad-band optical pulses generated by induced-phase modulation in a gas-filled hollow fiber using a modified SPIDER technique　　　　　　　　　　　　　　　
Keisaku Yamane, Naoki Karasawa, Satoru Kusaka, Masakatsu Hirasawa, Akira Suguro, Hidemi Shigekawa, Ryuji Morita, Mikio Yamashita
Pacific Rim Conference on Lasers and Electro-Optics, CLEO - Technical Digest, 457, 458, 2002年
英語, 研究論文（国際会議プロシーディングス）, Spectral behaviors of ultrabroad-band optical pulses generated by induced-phase modulation in a gas-filled hollow fiber using a modified SPIDER technique were discussed. Pulse-shaper output spectra of the ultrabroad-band optical pulses from 350 to 700 nm was shown. Results showed that the interferometric structure was lost in the spectral region from 310 to 333 nm in ∼1s but was clear in the 333 to 370 nm region.

Absorption-free optical control of spin systems: The quantum Zeno effect in optical pumping
T. Nakanishi, K. Yamane, M. Kitano
Physical Review A - Atomic, Molecular, and Optical Physics, 65, 1, 4, 2002年, ［査読有り］
英語, 研究論文（学術雑誌）, We show that atomic spin motion can be controlled by circularly polarized light without light absorption in the strong pumping limit. In this limit, the pumping light, which drives the empty spin state, destroys the Zeeman coherence effectively and freezes the coherent transition via the quantum Zeno effect. It is verified experimentally that the amount of light absorption decreases asymptotically to zero as the incident light intensity is increased. © 2001 The American Physical Society.

Quantum Zeno effect in optical fibers
K Yamane, M Ito, M Kitano
OPTICS COMMUNICATIONS, 192, 3-6, 299, 307, ELSEVIER SCIENCE BV, 2001年06月, ［査読有り］
英語, 研究論文（学術雑誌）, The quantum Zeno effect is a paradoxical phenomenon where the inhibition of transition or the guidance of system is realized with no losses in spite of the use of dissipative processes. It is universal and not limited to quantum systems. In this paper as a classical example we report the quantum Zeno effect in optical fibers. The fibers are spliced with transverse offset at fiber joints, and incident light transmits in the series of fibers. There are two kinds of light propagation modes in optical fibers - wave and ray modes. We find that the quantum Zeno effect appears only in the former mode and light is guided without power losses in the limit of the number of fiber joints N --> infinity despite of the discontinuity at joints. (C) 2001 Elsevier Science B.V. All rights reserved.

光の量子ゼノ効果
北野 正雄, 山根 啓作
レーザー研究, 28, 10, 650, 655, レ-ザ-学会, 2000年10月15日
日本語

23pYK-2 量子Zeno効果によるスピン制御
中西 俊搏, 山根 啓作, 北野 正雄
日本物理学会講演概要集, 55, 2, 106, 106, The Physical Society of Japan (JPS), 2000年09月10日
日本語

光ファイバにおける量子 Zeno 効果
山根 啓作, 伊藤 雅弘, 北野 正雄
電子情報通信学会技術研究報告. OPE, 光エレクトロニクス, 99, 544, 19, 24, 一般社団法人電子情報通信学会, 2000年01月19日
日本語, 量子Zeno効果は散逸過程が関与しているにもかかわらず損失無しに状態遷移の抑制あるいは系の誘導を行うことが出来る点において逆接的な現象である.Zeno効果は量子系に限定されない普遍的な現象である.本論文では古典系における例として軸をずらせて接続されたファイバー列における量子Zeno効果について報告する.ここではファイバ列に対して光を入射した場合の光の透過率を調べることで量子Zeno効果の検証を行なう.ファイバにおける光の伝搬様式には波動的な場合と光線的な場合が存在するが, 量子Zeno効果は波動的な伝搬をする場合のみ存在することが分かった.その場合, 接続部における不連続性にも関わらず光の透過率は接続段の増加とともに1に収束することが分かった.

光ファイバにおける量子 Zeno 効果
山根 啓作, 伊藤 雅弘, 北野 正雄
電子情報通信学会技術研究報告. LQE, レーザ・量子エレクトロニクス, 99, 546, 19, 24, 一般社団法人電子情報通信学会, 2000年01月19日
日本語, 量子Zeno効果は散逸過程が関与しているにもかかわらず損失無しに状態遷移の抑制あるいは系の誘導を行うことが出来る点において逆接的な現象である.Zeno効果は量子系に限定されない普遍的な現象である.本論文では古典系における例として軸をずらせて接続されたファイバー列における量子Zeno効果について報告する.ここではファイバ列に対して光を入射した場合の光の透過率を調べることで量子Zeno効果の検証を行なう.ファイバにおける光の伝搬様式には波動的な場合と光線的な場合が存在するが, 量子Zeno効果は波動的な伝搬をする場合にのみ存在することが分かった.その場合, 接続部における不連続性にも関わらず光の透過率は接続段の増加とともに1に収束することが分かった.

最近の量子光学の進展 光の量子ゼノ効果
北野 正雄, 山根 啓作
レーザー研究, 28, 10, 650, 655, The Laser Society of Japan, 2000年
日本語, The quantum Zeno effect (QZE) is seemingly paradoxical in a sense that an inhibition of transition or a guidance of system can be realized without loss of probability amplitudes in spite of the use of non-unitary processes. But it is quite universal and has been found in various quantum systems as well as in classical wave systems. In this report we will present two examples of QZE in the field of optics . One is theoptical pumping scheme in which atomic spin motion can be controlled without photon absorption in the fast pumping limit. The other example is the light propagation through a series of offset-spliced fibers . Two propagation modes, wave and ray, are possible in optical fibers, and QZE is found to occur only in the former mode.

Spin manipulation by absorption-free optical pumping
M Kitano, K Yamane, T Ikushima
PHYSICAL REVIEW A, 59, 5, 3710, 3713, AMERICAN PHYSICAL SOC, 1999年05月, ［査読有り］
英語, 研究論文（学術雑誌）, We present an optical pumping scheme by which atomic spin motion can be controlled without photon absorption in the fast pumping limit. The phenomenon can be understood in terms of the quantum Zeno effect and the interaction-free measurement in a spin-photon system. [S1050-2947(99)01005-7].

再循環光学系における非同期和周波発生を用いた周波数スイープパルス列の生成
爲本龍汰, 本田亜沙美, 漕江駿太, 山根啓作, 鈴木雅人, 戸田泰則, 尾松孝茂, 尾松孝茂, 森田隆二, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 70th, 2023年

超高速バーストイメージングのための偏光変換に基づく分光結像光学系の開発
漕江駿太, 爲本龍汰, 本田亜沙美, 山根啓作, 戸田泰則, 尾松孝茂, 森田隆二, Optics & Photonics Japan講演予稿集(CD-ROM), 2023, 2023年

Sub-Gfpsバーストイメージングに向けた再循環フィルタリングによる周波数離散化パルス列生成
爲本龍汰, 漕江駿太, 本田亜沙美, 山根啓作, 戸田泰則, 尾松孝茂, 森田隆二, Optics & Photonics Japan講演予稿集(CD-ROM), 2023, 2023年

構造化光のチャープパルスを用いた超高速空間モード変調【JST・京大機械翻訳】
MORITA Ryuji, YAMANE Keisaku, SUZUKI Masato, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 83rd, 2022年

非同期パルス列間の和周波発生を用いた周波数スイープパルス列の生成
爲本龍汰, 本田亜沙美, 山根啓作, 鈴木雅人, 戸田泰則, 尾松孝茂, 尾松孝茂, 森田隆二, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 83rd, 2022年

光渦レーザー誘起前方転写法による超解像金属ナノ微粒子パターニング
川口晴生, 梅里慧, 高橋幹太, 柚山健一, 山根啓作, 宮本克彦, 尾松孝茂, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 68th, 595, 595, 2021年02月26日
公益社団法人 応用物理学会, 日本語

伝搬特性を改善した新型渦Airyビームの提案【JST・京大機械翻訳】
SUZUKI Masato, YAMANE Keisaku, OMATSU Takashige, MORITA Ryuji, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 82nd, 2021年

光渦の軌道角運動量分解精度向上のための偏光回折素子光学系開発
飯塚健介, 山根啓作, 川村一貴, 坂本盛嗣, 小野浩司, 岡和彦, 戸田泰則, 森田隆二, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 68th, 2021年
IEEE, 英語

光渦の二光子吸収によって形成されたキラル表面レリーフ
篠崎諒, 増田圭吾, 一條瑞樹, 山根啓作, 宮本克彦, 宮本克彦, 尾松孝茂, 尾松孝茂, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 80th, 2019年

空間変調光帰還型面発光レーザーのOAMモード偏光特性
仲川幸輝, 山根啓作, 森田隆二, 戸田泰則, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 80th, 2019年

光渦の軌道角運動量分解精度向上のための光波複製光学系の開発
渡辺悠歩, 山根啓作, 岡和彦, 戸田泰則, 森田隆二, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 79th, 2018年

軸対称偏光素子を用いたトラップ粒子の回転制御(II)
小原威吹, 坂本盛嗣, 山根啓作, 森田隆二, 岡和彦, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 64th, ROMBUNNO.15a‐312‐3, 2017年03月01日
日本語

高強度・超高速回転リング状光格子の発生
柿澤康平, 岩佐康平, 山根啓作, 岡和彦, 戸田泰則, 森田隆二, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 64th, ROMBUNNO.16p‐311‐8, 2017年03月01日
日本語

幾何学的変換に基づく光渦の高精度軌道角運動量分解計測
山根啓作, 戸田泰則, 森田隆二, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 64th, ROMBUNNO.16p‐311‐7, 2017年03月01日
日本語

光渦の干渉パターンを用いた微小粒子の回転制御
小原威吹, 坂本盛嗣, 山根啓作, 森田隆二, 岡和彦, 応用物理学会北海道支部/日本光学会北海道支部合同学術講演会講演予稿集, 52nd-13th, 2017年

時空間分解偏光解析から明らかとなった励起子コヒーレントダイナミクスにおける回転対称性破れ
重松恭平, 鈴木雅人, 山根啓作, 森田隆二, 戸田泰則, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 63rd, ROMBUNNO.20P-P3-1, 2016年03月03日
日本語

拡張ストークスパラメータにおける拡張偏光度スペクトルを用いた光波の空間回転対称性解析の検討
鈴木雅人, 山根啓作, 岡和彦, 戸田泰則, 森田隆二, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 63rd, ROMBUNNO.21P-S622-20, 2016年03月03日
日本語

光渦によって形成される単結晶性シリコンニードルのパルス幅依存性
藤原穂波, 高橋冬都, 泉澤魁, 比田井洋史, 宮本克彦, 山根啓作, 森田隆二, 尾松孝茂, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 63rd, ROMBUNNO.19P-H116-5, 2016年03月03日
日本語

チャープパルスを用いた直線偏光の偏光方位の超高速回転
永井美祐, 坂本盛嗣, 坂本盛嗣, 山根啓作, 森田隆二, 岡和彦, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 63rd, ROMBUNNO.19P-S621-7, 2016年03月03日
日本語

超微細加工のための高強度・高繰り返しYb:YAG超短光パルスレーザーの構築
角田恵一郎, 山根啓作, 山根啓作, 戸田泰則, 戸田泰則, 森田隆二, 森田隆二, 応用物理学会北海道支部・日本光学会北海道地区合同学術講演会講演予稿集, 51st-12th, 60, 2016年01月09日
日本語

パルス幅可変光渦を用いたナノニードル形成とそのメカニズムに関する研究
里水里, 山根啓作, 山根啓作, 戸田泰則, 戸田泰則, 森田隆二, 森田隆二, 応用物理学会北海道支部・日本光学会北海道地区合同学術講演会講演予稿集, 51st-12th, 61, 2016年01月09日
日本語

軸対称偏光子を用いたトラップ粒子の回転制御
小原威吹, 坂本盛嗣, 山根啓作, 森田隆二, 岡和彦, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 63rd, 2016年

空間変調光注入同期による面発光レーザーのトポロジカルチャージ制御
西坂拓馬, 重松恭平, 山根啓作, 山根啓作, 森田隆二, 森田隆二, 淡路祥成, 戸田泰則, 戸田泰則, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 63rd, 2016年

光渦パルスのチャープ特性を利用したプログラマブル超高速回転リング状光格子の生成
柿澤康平, 山根啓作, 岡和彦, 戸田泰則, 森田隆二, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 77th, 2016年

Rotational Symmetry Breaking in Coherent Dynamics of GaN Excitons Excited by Radially Polarized Pulses
Kyohhei Shigematsu, Masato Suzuki, Keisaku Yamane, Ryuji Morita, Yasunori Toda, 2016 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), 2016年, ［査読有り］
We performed four-wave-mixing (FWM) spectroscopy using radially polarized pulses on uniaxially strained GaN excitons. The FWM dynamics show a deformation of the polarization distributions attributable to the rotational symmetry breaking in the exciton coherent dynamics., IEEE, 英語

空間光位相変調器と軸対称偏光変換素子とによる強度分布制御された軸対称偏光パルスの生成
鈴木雅人, 山根啓作, 山根啓作, 中嶌奨太, 坂本盛嗣, 岡和彦, 戸田泰則, 戸田泰則, 森田隆二, 森田隆二, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 76th, ROMBUNNO.14A-2G-3, 2015年08月31日
日本語

コリニア型配置を用いた光電場再生に基づく光渦のラゲールガウスモード展開
中嶌奨太, 山根啓作, 山根啓作, 鈴木雅人, 戸田泰則, 戸田泰則, 森田隆二, 森田隆二, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 76th, ROMBUNNO.14A-2G-2, 2015年08月31日
日本語

広がりを見せる光渦 軸対称偏光素子を用いた光渦の生成と白色光渦およびリング状光格子生成への応用
岡和彦, 坂本盛嗣, 山根啓作, 森田隆二, O plus E, 425, 263, 268, 2015年03月25日
日本語

コヒーレント結合系を用いて生成された超短径偏光パルスの拡張ストークスパラメータによる定量的解析
鈴木雅人, 山根啓作, 岡和彦, 戸田泰則, 森田隆二, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 62nd, ROMBUNNO.12P-A15-12, 2015年02月26日
日本語

軸対称偏光ビームの空間位相解析
山根啓作, 横瀬尚也, 鈴木雅人, 戸田泰則, 森田隆二, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 62nd, ROMBUNNO.12P-A15-13, 2015年02月26日
日本語

光電場再生に基づいた光渦のラゲールガウスモード展開
山根啓作, 中嶌奨太, 鈴木雅人, 戸田泰則, 森田隆二, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 62nd, ROMBUNNO.12P-A15-14, 2015年02月26日
日本語

21pCP-4 軸対称偏光パルスを用いたGaN励起子微細構造の四光波混合分光
重松 恭平, 森本 祥平, 鈴木 雅人, 山根 啓作, 森田 隆二, 戸田 泰則, 日本物理学会講演概要集, 70, 0, 1471, 1471, 2015年
一般社団法人 日本物理学会, 日本語

Over 1-mJ Intense Ultrashort Optical-Vortex Pulse Generation with Programmable Topological-Charge Control by Chirped-Pulse Amplification
Keisaku Yamane, Asami Honda, Yasunori Toda, Ryuji Morita, ULTRAFAST PHENOMENA XIX, 162, 809, 812, 2015年
We demonstrated the generation of over 1-mJ intense optical-vortex pulses of which topological charges were programmable controlled by computer-generated holograms. The pulse duration was characterized to be 27 fs by two-dimensional spectral shearing interferometry., SPRINGER-VERLAG BERLIN, 英語

ピコ秒時間スケールで高速回転するリング状光格子の生成
坂本盛嗣, 山根啓作, 村上尚史, 森田隆二, 岡和彦, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 75th, ROMBUNNO.19A-C2-3, 2014年09月01日
日本語

ホログラムの最適化によるラゲールガウスビーム発生の高精度化
本田亜沙美, 山根啓作, 鈴木雅人, 戸田泰則, 森田隆二, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 75th, ROMBUNNO.19P-C1-12, 2014年09月01日
日本語

空間変調光帰還による面発光レーザーの高次横モード制御
西坂拓馬, 重松恭平, 由利洋樹, 山根啓作, 森田隆二, 淡路祥成, 戸田泰則, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 75th, ROMBUNNO.19P-C1-15, 2014年09月01日
日本語

多重横モード面発光レーザーにおける特異点ダイナミクス
由利洋樹, 重松恭平, 西坂拓馬, 山根啓作, 森田隆二, 淡路祥成, 戸田泰則, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 75th, ROMBUNNO.19P-C1-16, 2014年09月01日
日本語

拡張ストークスパラメータによる高次偏光渦の解析
鈴木雅人, 山根啓作, 岡和彦, 戸田泰則, 森田隆二, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 75th, ROMBUNNO.19P-C1-14, 2014年09月01日
日本語

円筒座標系を基礎とする拡張ストークスパラメータによる軸対称偏光状態の解析 II
横瀬尚也, 鈴木雅人, 山根啓作, 岡和彦, 戸田泰則, 森田隆二, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 75th, ROMBUNNO.19P-C1-13, 2014年09月01日
日本語

Quantitative analysis of l = 2 radially polarized ultrashort pulses by using extended stokes parameters
Masato Suzuki, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda, Ryuji Morita, Optics InfoBase Conference Papers, 2014年07月21日

mJ級高強度トポロジカルチャージ可変超短光渦パルス発生
山根啓作, 本田亜沙美, 戸田泰則, 森田隆二, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 61st, ROMBUNNO.18A-F7-1, 2014年03月03日
日本語

円筒座標系を基礎とする拡張ストークスパラメータによる軸対称偏光状態の解析
鈴木雅人, 山根啓作, 塩田康之, 岡和彦, 戸田泰則, 森田隆二, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 61st, ROMBUNNO.17A-F6-8, 2014年03月03日
日本語

Generation of the ring-shaped optical lattice using axially-symmetric polarization elements (II)
Moritsugu Sakamoto, Keisaku Yamane, Keisaku Yamane, Naoshi Murakami, Ryuji Morita, Ryuji Morita, Kazuhiko Oka, Frontiers in Optics, FiO 2014, 2014年01月01日
© 2014 Optical Society of America. A novel optical system of a ring-shaped optical-lattice generator using axially-symmetric polarization elements is presented. A series of axially-symmetric polarization elements incorporated into the configuration enables generating any combination of vortices with even-numbered topolog-ical charges.

高強度かつ広帯域な光渦パルスに適応可能な偏光渦変換器の開発
塩田康之, 山根啓作, 覚間誠一, 戸田泰則, 森田隆二, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 74th, ROMBUNNO.19P-A3-3, 2013年08月31日
日本語

複合光渦励起による励起子軌道角運動量スペクトルダイナミクス
重松恭平, 戸田泰則, 山根啓作, 森田隆二, 日本物理学会講演概要集, 68, 2, 699, 699, 2013年08月26日
一般社団法人日本物理学会, 日本語

非線型屈折率効果を伴う物質の異方性を用いた光子のスピン軌道角運動量変換 IV
鈴木雅人, 山根啓作, 戸田泰則, 森田隆二, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 60th, ROMBUNNO.28A-D2-7, 2013年03月11日
日本語

トポロジカルチャージ可変な高強度超短光渦パルス光源の開発
山根啓作, 本田亜沙美, 戸田泰則, 森田隆二, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 60th, ROMBUNNO.28A-D2-6, 2013年03月11日
日本語

一軸性結晶内における軸対称偏光ビームの非線型カップリングと空間的に拡張したストークスパラメータによるその理解
鈴木雅人, 山根啓作, 戸田泰則, 森田隆二, Optics & Photonics Japan講演予稿集(CD-ROM), 2013, ROMBUNNO.12AE4, 2013年
日本語

チャープパルス増幅を用いたトポロジカルチャージ可変な高強度超短光渦パルスの発生
本田亜沙美, 山根啓作, 横瀬尚也, 重松恭平, 戸田泰則, 森田隆二, Optics & Photonics Japan講演予稿集(CD-ROM), 2013, ROMBUNNO.12AE3, 2013年
日本語

Measurement of orbital angular momentum spectrum of optical vortices based on electric-field reconstruction in spatial domain
Keisaku Yamane, Zhili Yang, Kyouhei Shigematsu, Yasunori Toda, Ryuji Morita, 2013 CONFERENCE ON LASERS AND ELECTRO-OPTICS EUROPE AND INTERNATIONAL QUANTUM ELECTRONICS CONFERENCE (CLEO EUROPE/IQEC), 2013年, ［査読有り］
IEEE, 英語

高次光渦励起によるGaN励起子の軌道角運動量分解四光波混合分光
重松恭平, 戸田泰則, 山根啓作, 森田隆二, 応用物理学会学術講演会講演予稿集(CD-ROM), 73rd, ROMBUNNO.13A-B2-3, 2012年08月27日
日本語

非線型屈折率効果を伴う物質の異方性を用いた光子のスピン軌道角運動量変換 III
鈴木雅人, 山根啓作, 戸田泰則, 森田隆二, 応用物理学会学術講演会講演予稿集(CD-ROM), 73rd, ROMBUNNO.13A-B2-2, 2012年08月27日
日本語

数サイクル域超短光渦パルス発生
山根啓作, 戸田泰則, 森田隆二, 応用物理学関係連合講演会講演予稿集(CD-ROM), 59th, ROMBUNNO.18A-E9-9, 2012年02月29日
日本語

Generation of ultrashort optical vortex pulses using optical parametric amplification
Keisaku Yamane, Yasunori Toda, Ryuji Morita, 2012 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), 2012年, ［査読有り］
The generation of 2.3-cycle, 5.9-fs, 56-mu J ultrashort optical-vortex pulses by optical parametric amplification was performed. To the best of our knowledge, it is the first generation of optical vortex pulses in the few-cycle regime. (C) 2011 Optical Society of America, IEEE, 英語

非線型屈折率効果を伴う物質の異方性を用いた光子のスピン軌道角運動量変換 II
鈴木雅人, 山根啓作, 戸田泰則, 戸田泰則, 森田隆二, 森田隆二, 応用物理学会学術講演会講演予稿集(CD-ROM), 72nd, ROMBUNNO.30P-ZH-10, 2011年08月16日
日本語

Femtosecond photoisomerization study on azobenzene-derivative bound by DNA
T. Chen, K. Igarashi, A. Yamaguchi, N. Nakagawa, K. Yamane, T. Fujii, H. Asanuma, M. Yamashita, Optics InfoBase Conference Papers, 2010年12月01日
First observation of femtosecond absorbance change in azobenzene-derivative (AzD) bound by double-strand DNA, that by single-strand DNA and Azd shows trans-to-cis photoisomerization rate per pulse in the former is much lower than in the latter. © OSA / UP 2010.

Complete Characterization of Single Attosecond Pulses by the Modified Spectral Phase Interferometry with an All-Optical Apparatus
J. Zhu, S. Fang, T. Chen, K. Yamane, M. Yamashita, 2010 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO) AND QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE (QELS), 2010年
We present the complete characterization of single attosecond pulses by the modified SPIDER method with a frequency-dependent spectral shear. The validity of this method shows no principle limitation of characterizing arbitrary short single attosecond pulses. (C) 2010 Optical Society of America, IEEE, 英語

Carrier-envelop-phase stabilized 3.3-fs optical pulses in the monocycle region
K. Yamane, T. Naoi, R. Morita, K. Sugiyama, M. Kitano, M. Yamashita, Optics InfoBase Conference Papers, 2006年01月01日
A system generating 3.3-fs optical pulses with a carrier-envelope-phase stabilized, quasi-monocycle waveform (500-nJ pulse energy, 470-to-1060 nm spectral width,1-kHz repetition rate) has been developed for the first time. © 2005 Optical Society of America.

CEP安定化された3.3フェムト秒パルスレーザーシステムの構築
直井俊幸, 山根啓作, 森田隆二, 杉山和彦, 北野正雄, 山下幹雄, 応用物理学関係連合講演会講演予稿集, 52nd, 3, 2005年

ウェーブレット変換によるサイクル域光パルススペクトル位相解析-サイクル域光パルス自動フィードバックチャープ補償を目指して-
成田啓介, 足立宗之, 山根啓作, 森田隆二, DENG Yuqiang, ZHANG Zhigang, 山下幹雄, 応用物理学関係連合講演会講演予稿集, 52nd, 3, 2005年

フォトニッククリスタルファイバを用いたフィードバック光パルス圧縮-高繰り返しモノサイクルパルス発生をめざして-
足立宗之, 山根啓作, 成田啓介, 森田隆二, 山下幹雄, 応用物理学関係連合講演会講演予稿集, 52nd, 3, 2005年

2.8フェムト秒パルスレーザーシステムのためのCEP安定化
直井俊幸, 鬼頭俊彦, 山根啓作, 森田隆二, 杉山和彦, 北野正雄, 山下幹雄, 応用物理学会学術講演会講演予稿集, 65th, 3, 2004年

微細構造ファイバー出力超広帯域フェムト秒光パルスのフィードバックチャープ補償 III
西村大, 足立宗之, 山根啓作, 勝呂彰, 小林壮一, 森田隆二, 山下幹雄, 応用物理学関係連合講演会講演予稿集, 51st, 3, 2004年

ウィグナー分布関数による~3-fs光パルスフィードバック位相補償の時間周波数解析
森田隆二, 山根啓作, 勝呂彰, 山下幹雄, 応用物理学関係連合講演会講演予稿集, 51st, 3, 2004年

2.8fsフーリエ変換限界光パルス発生
山根啓作, 鬼頭俊彦, 森田隆二, 山下幹雄, 応用物理学会学術講演会講演予稿集, 65th, 3, 2004年

微細構造ファイバー出力光パルスのフィードバックチャープ補償
足立宗之, 山根啓作, 勝呂彰, 小林壮一, 森田隆二, 山下幹雄, 応用物理学会学術講演会講演予稿集, 65th, 3, 2004年

フリンジ分解自己相関法による極短光パルス計測の限界と有効性に関する実験実証
山根啓作, 鬼頭俊彦, 勝呂彰, 森田隆二, 山下幹雄, 応用物理学関係連合講演会講演予稿集, 51st, 3, 2004年

サイクル光パルスのフリンジ分解型自己相関法における非線形効果の検討
鬼頭俊彦, 山根啓作, 勝呂彰, 森田隆二, 山下幹雄, 応用物理学会学術講演会講演予稿集, 64th, 3, 2003年

微細構造ファイバー出力超広帯域フェムト秒光パルスのフィードバックチャープ補償 II
足立宗之, 山根啓作, 勝呂彰, 小林壮一, 森田隆二, 山下幹雄, 応用物理学会学術講演会講演予稿集, 64th, 3, 2003年

フィードバックチャープ補償による4fs以下の極短光招ルス発生 II
山根啓作, ZHANG Z, 鬼頭俊彦, 勝呂彰, 森田隆二, 山下幹雄, 応用物理学関係連合講演会講演予稿集, 50th, 3, 2003年

ウィグナー分布関数を用いた4-fs光パルスチャープ補償の解析
竹中隼人, 森田隆二, 山根啓作, 勝呂彰, 山下幹雄, 応用物理学関係連合講演会講演予稿集, 50th, 3, 2003年

微細構造ファイバー出力超広帯域フェムト秒光パルスのフィードバックチャープ補償
足立宗之, 山根啓作, 勝呂彰, 小林壮一, 森田隆二, 山下幹雄, 応用物理学関係連合講演会講演予稿集, 50th, 3, 2003年

フィードバックチャープ補償による3.4fs光パルスの発生
山下幹雄, 山根啓作, 森田隆二, 応用物理学会学術講演会講演予稿集, 64th, 2003年

サイクル時間域光パルス特性測定法の比較
森田隆二, 平沢正勝, 唐沢直樹, 山根啓作, 日下哲, 中川直也, 勝呂彰, 山下幹雄, 応用物理学会学術講演会講演予稿集, 63rd, 3, 2002年

アルゴン充填中空ファイバー中で発生された超広帯域光パルスの高感度特性評価
山根啓作, 日下哲, 渡辺吉徳, 勝呂彰, 森田隆二, 重川秀実, 山下幹雄, 応用物理学関係連合講演会講演予稿集, 49th, 3, 2002年

高感度変形SPIDERによるサイクル光パルスのシングルショット位相測定とチャープ補償
中川直也, 山根啓作, 山本和樹, 橋本晃仁, 渡辺吉徳, 鬼頭俊彦, 森田隆二, 勝呂彰, 山下幹雄, 応用物理学会学術講演会講演予稿集, 63rd, 3, 2002年

フィードバックチャープ補償による4fs以下の極短光パルス発生
山根啓作, ZHANG Z, 渡辺吉徳, 勝呂彰, 森田隆二, 山下幹雄, 応用物理学会学術講演会講演予稿集, 63rd, 3, 2002年

極限光パルス発生のための中空ファイバー誘起位相変調光の空間位相変調チャープ補償と計測 (科学技術振興事業団S)
山根啓作, 日下哲, 渡辺吉徳, 勝呂彰, 森田隆二, 山下幹雄, 量子効果等の物理現象 第5回定例シンポジウム第2回終了シンポジウム予稿集 平成13年, 2001年

高感度変形SPIDER-IAC計測装置の試作
日下哲, 日下哲, LI L., LI L., 渡辺吉徳, 渡辺吉徳, 山根啓作, 森田隆二, 森田隆二, 勝呂彰, 重川秀美, 重川秀美, 山下幹雄, 山下幹雄, 応用物理学会学術講演会講演予稿集, 62nd, 3, 2001年

量子Zeno効果による原子スピン制御
山根 啓作, 生島 剛, 北野 正雄, 小倉 久直, 日本物理学会講演概要集. 秋の分科会, 1996, 2, 479, 479, 1996年09月13日
一般社団法人日本物理学会, 日本語

29a-YP-1 半導体レーザによるRb原子のレーザ冷却III
山根 啓作, 吉田 明生, 十倉 俊之, 北野 正雄, 小倉 久直, 日本物理学会講演概要集. 年会, 50, 2, 465, 465, 1995年03月16日
一般社団法人日本物理学会, 日本語

29a-E-5 半導体レーザによるRb原子のレーザ冷却 II
吉田 明生, 山根 啓作, 十倉 俊之, 北野 正雄, 小倉 久直, 日本物理学会講演概要集. 年会, 49, 2, 374, 374, 1994年03月16日
一般社団法人日本物理学会, 日本語

13a-DA-8 半導体レーザによるRb原子のレーザ冷却
吉田 明生, 上野 洋史, 山根 啓作, 北野 正雄, 小倉 久直, 日本物理学会講演概要集. 秋の分科会, 1993, 2, 438, 438, 1993年09月20日
一般社団法人日本物理学会, 日本語

レーザー誘起前方転写におけるダブルパルス励起の効果　　　　　　　　　　　　　　　
爲本 龍汰, 漕江 駿太, 佐藤 光太朗, 山根 啓作, 戸田 泰則, 尾松 孝茂, 森田 隆二
第85回応用物理学会秋季学術講演会, 2024年09月19日, 日本語, ポスター発表
2024年09月16日 - 2024年09月20日

Sub-Gfps burst imaging of initial process in optical vortex laser-induced forward transfer　　　　　　　　　　　　　　　
Ryota Tamemoto, Syunta Kogie, Kotaro Sato, Keisaku Yamane, Yasunori Toda, Takashige Omatsu, Ryuji Morita
The 23rd International Conference on Ultrafast Phenomena, 2024年07月16日, 英語, ポスター発表
2024年07月15日 - 2024年07月19日

Snapshot visualization of initial process in laser-induced forward transfer　　　　　　　　　　　　　　　
Ryota Tamemoto, Syunta Kogie, Kotaro Sato, Keisaku Yamane, Yasunori Toda, Takashige Omatsu, Ryuji Morita
Optical Manipulation and Structured Materials Conference (OMC 2024), 2024年04月24日, 英語, 口頭発表（一般）
2024年04月22日 - 2024年04月26日

光渦パルスを用いた銅酸化物高温超伝導体擬ギャップの時空間制御　　　　　　　　　　　　　　　
松本 和也, 清水 大成, 土屋 聡, 山根 啓作, 森田 隆二, 小田 研, 黒澤 徹, 戸田 泰則
第71回応用物理学会春季学術講演会, 2024年03月23日, 日本語, 口頭発表（一般）
2024年03月22日 - 2024年03月25日

ピコ秒域パルス列を用いた光渦レーザー誘起前方転写　　　　　　　　　　　　　　　
山根 啓作, 爲本 龍汰, 佐藤 光太朗, 漕江 駿太, 戸田 泰則, 尾松 孝茂, 森田 隆二
第71回応用物理学会春季学術講演会, 2024年03月23日, 日本語, 口頭発表（一般）
2024年03月22日 - 2024年03月25日

光渦レーザー誘起前方転写法における初期過程のスナップショットイメージング　　　　　　　　　　　　　　　
爲本 龍汰, 漕江 駿太, 佐藤 光太朗, 山根 啓作, 戸田 泰則, 尾松 孝茂, 森田 隆二
第71回応用物理学会春季学術講演会, 2024年03月23日, 日本語, 口頭発表（一般）
2024年03月22日 - 2024年03月25日

トポロジカル光波の時空間制御とその応用展開　　　　　　　　　　　　　　　
山根 啓作
第2回超高速光エレクトロニクス研究会, 2024年03月12日, 日本語, 口頭発表（招待・特別）
2024年03月12日 - 2024年03月12日, ［招待講演］

和周波発生による周波数スイープパルス列生成を用いたsub-Gfpsシングルショットイメージング装置の開発　　　　　　　　　　　　　　　
爲本龍汰, 漕江駿太, 本田亜沙美, 山根啓作, 戸田泰則, 尾松孝茂, 森田隆二
レーザー学会 第44回年次大会, 2024年01月18日, 日本語, 口頭発表（一般）
2024年01月16日 - 2024年01月19日

超高速バーストイメージングのための偏光変換に基づく分光結像光学系の開発　　　　　　　　　　　　　　　
漕江駿太, 爲本龍汰, 本田亜沙美, 山根啓作, 戸田泰則, 尾松孝茂, 森田隆二
Optics & Photonics Japan 2023, 2023年11月27日, 日本語, 口頭発表（一般）
2023年11月27日 - 2023年11月29日

Sub-Gfpsバーストイメージングに向けた再循環フィルタリングによる周波数離散化パルス列生成　　　　　　　　　　　　　　　
爲本龍汰, 漕江駿太, 本田亜沙美, 山根啓作, 戸田泰則, 尾松孝茂, 森田隆二
Optics & Photonics Japan 2023, 2023年11月27日, 日本語, 口頭発表（一般）
2023年11月27日 - 2023年11月29日

光渦パルス誘起局在超伝導の時空間ダイナミクス　　　　　　　　　　　　　　　
戸田泰則, 土屋聡, 山根啓作, 森田隆二, 小田研, 黒沢徹
第84回応用物理学会秋季学術講演会, 2023年09月23日, 日本語, 口頭発表（一般）
2023年09月19日 - 2023年09月23日

Generation of frequency-swept optical pulse train based on sum frequency generation for sub-Gfps snapshot imaging　　　　　　　　　　　　　　　
Ryota Tamemoto, Asami Honda, Syunta Kogie, Keisaku Yamane, Masato Suzuki, Yasunori Toda, Takasige Omatsu, Ryuji Morita
The 12th Asia-Pacific Laser Symposium(APLS 2023), 2023年09月05日, 英語, 口頭発表（一般）
2023年09月04日 - 2023年09月07日

光渦レーザー誘起前方転写法による高精細金ナノインクプリンティング　　　　　　　　　　　　　　　
甲斐清香, 川口晴生, 高橋幹太, WEI Rong, 山根啓作, 柚山健一, 川野聡恭, 森田隆二, 青木伸之, 青木伸之, 宮本克彦, 宮本克彦, 尾松孝茂, 尾松孝茂
第70回応用物理学会春季学術講演会, 2023年03月18日, 日本語, 口頭発表（一般）
2023年03月15日 - 2023年03月18日

再循環光学系における非同期和周波発生を用いた周波数スイープパルス列の生成　　　　　　　　　　　　　　　
爲本龍汰, 本田亜沙美, 漕江駿太, 山根啓作, 鈴木雅人, 戸田泰則, 尾松孝茂, 尾松孝茂, 森田隆二
第70回応用物理学会春季学術講演会, 2023年03月17日, 日本語, 口頭発表（一般）
2023年03月15日 - 2023年03月18日

光渦パルス誘起コヒーレントクエンチ超伝導の時空間特性　　　　　　　　　　　　　　　
尾上想一郎, 戸田泰則, 土屋聡, 山根啓作, 森田隆二, 小田研
第70回応用物理学会春季学術講演会, 2023年03月16日, 日本語, 口頭発表（一般）
2023年03月15日 - 2023年03月18日

Direct print of close-packed gold nanoparticle microdots with optical vortex illumination
Haruki Kawaguchi, Kanta Takahashi, Rong Wei, Keisaku Yamane, Ken-ichi Yuyama, Satoyuki Kawano, Ryuji Morita, Nobuyuki Aoki, Katsuhiko Miyamoto, Takashige Omatsu
Optical Manipulation and Structured Materials Conference (OMC 2022), 2022年12月08日, SPIE
2022年12月08日 - 2022年12月08日

非同期パルス列間の和周波発生を用いた周波数スイープパルス列の生成　　　　　　　　　　　　　　　
爲本龍汰, 本田亜沙美, 山根啓作, 鈴木雅人, 戸田泰則, 尾松孝茂, 尾松孝茂, 森田隆二
第83回応用物理学会秋季学術講演会, 2022年09月23日, 日本語, 口頭発表（一般）
2022年09月20日 - 2022年09月23日

光渦誘起前方移動による金ナノ粒子の超高精細マイクロドット印刷【JST・京大機械翻訳】　　　　　　　　　　　　　　　
KAWAGUCHI Haruki, TAKAHASHI Kanta, WEI Rong, YAMANE Keisaku, MORITA Ryuji, YUYAMA Ken-ichi, KAWANO Satoyuki, MIYAMOTO Katsuhiko, MIYAMOTO Katsuhiko, AOKI Nobuyuki, AOKI Nobuyuki, OMATSU Takashige, OMATSU Takashige
第83回応用物理学会秋季学術講演会, 2022年09月23日, 英語, 口頭発表（一般）
2022年09月20日 - 2022年09月23日

Ultrafast spatial mode modulation by using chirped pulses of structured light　　　　　　　　　　　　　　　
MORITA Ryuji, YAMANE Keisaku, SUZUKI Masato
JSAP-Optica-SPP Joint Symposia 2022, 2022年09月21日, 英語, 口頭発表（招待・特別）
2022年09月20日 - 2022年09月23日

Coherent quench of superconducting state using optical vortex pulses
Y. Toda, S. Tsuchiya, K. Yamane, R. Morita, M. Oda, T. Mertelj, D. Mihailovic
The 15th Pacific Rim Conference on Lasers and Electro-Optics (CLEO Pacific Rim, CLEO-PR 2022), 2022年08月02日, Optica Publishing Group, 英語, 口頭発表（一般）
2022年07月31日 - 2022年08月05日, Recently, topological lightwaves, represented by optical vortices, have become easily generated and are expected to have many novel applications. In this work, we report on coherent quench spectroscopy of a cuprate superconductor using optical vortex pulses to reveal the spatially modulated superconducting (SC) state. The transient response after quenching by the optical vortex pulse shows the spatially localized SC response that remains unquenched around the dark spot of the optical vortex. The spatially resolved imaging of the optical vortex-induced SC improves the spatial resolution in a similar principle to super-resolution microscopy.

Ultrafast snapshot imaging at sub-GHz framerate by using recirculation filtering of ultrashort optical pulses
Asami Honda, Ryota Tamemoto, Keisaku Yamane, Masato Suzuki, Yasunori Toda, Takashige Omatsu, Ryuji Morita
The 15th Pacific Rim Conference on Lasers and Electro-Optics (CLEO Pacific Rim, CLEO-PR 2022), 2022年08月01日, 英語, 口頭発表（一般）
2022年07月31日 - 2022年08月05日, We successfully demonstrated ultrafast snapshot imaging based on time-to-frequency mapping method with four frames and ∼ 5.5 ns time interval (i.e. sub-GHz framerate) by using our newly-developed recirculation system without ultrafast image sensor.

トポロジカル光波の生成と評価　　　　　　　　　　　　　　　
鈴木 雅人, 山根 啓作
第4回超高速光エレクトロニクス研究会, 2022年06月21日, 日本語, 口頭発表（招待・特別）
2022年06月21日 - 2022年06月21日, ［招待講演］

Development of sub-Gfps ultrafast snapshot imaging system based on recirculation filtering of ultrashort optical pulses
Asami Honda, Keisaku Yamane, Masato Suzuki, Jin Kawaguchi, Yasunori Toda, Takashige Omatsu, Ryuji Morita
Conference on Lasers and Electro-Optics, CLEO 2022, 2022年05月19日, 英語, 口頭発表（一般）
2022年05月15日 - 2022年05月20日, We demonstrated ultrafast snapshot imaging with a sub-GHz framerate on the basis of our newly proposed recirculation-filtering method, which enables us to generate a wavelength-division multiplexed pulse train with a time interval in nanosecond regime.

光渦誘起前方移動による金ドットの超高精度マイクロパターニング　　　　　　　　　　　　　　　
TAKAHASHI Kanta, KAWAGUCHI Haruki, WEI Rong, YAMANE Keisaku, YUYAMA Ken-ichi, MIYAMOTO Katsuhiko, MIYAMOTO Katsuhiko, OMATSU Takashige, OMATSU Takashige
Optics & Photonics Japan講演予稿集(CD-ROM), 2022年
2022年 - 2022年

光渦レーザー誘起前方転写法による金ナノインクプリンティング　　　　　　　　　　　　　　　
WEI Rong, 川口晴生, 山根啓作, 柚山健一, 川野聡恭, 森田隆二, 青木伸之, 青木伸之, 宮本克彦, 宮本克彦, 尾松孝茂, 尾松孝茂
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2022年
2022年 - 2022年

Direct Optical Vortex Laser Printing of a Microdot with Close-Packed and Sintered Gold Nanoparticles
Haruki Kawaguchi, Rong Wei, Keisaku Yamane, Ken-ichi Yuyama, Satoyuki Kawano, Ryuji Morita, Kohei Toyoda, Katsuhiko Miyamoto, Takashige Omatsu
Conference on Lasers and Electro-Optics, 2022年, Optica Publishing Group
2022年 - 2022年, We demonstrate the direct printing of an ultrafine microdot formed of gold nanoparticles by employing optical vortex laser induced forward transfer. Spin and orbital angular momentum induces the close-packing and sintering of gold nanoparticles.

光渦パルスを用いた超伝導コヒーレントクエンチの実現　　　　　　　　　　　　　　　
戸田泰則, 山岡利盛, 土屋聡, 山根啓作, 森田隆二, 小田研
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2022年, 日本語, 口頭発表（一般）
2022年 - 2022年

Vortex Airy beam realized by superposition of two Airy beams
Masato Suzuki, Keisaku Yamane, Takashige Omatsu, Ryuji Morita
The 2021 Frontiers in Optics and Laser Science Conference, 2021年11月01日, 英語, 口頭発表（一般）
2021年11月01日 - 2021年11月04日, We propose a new-type vortex Airy beam with both orbital angular momentum and non-diffraction property as a superposition of laterally-sheared two Airy beams. The propagation characteristics are hugely improved compared with the conventional ones.

液晶のトポロジカル欠陥を用いた光渦アレイの回折現象　　　　　　　　　　　　　　　
佐々木裕司, 村上尚史, 山根啓作, 折原宏
日本物理学会2021年秋季大会, 2021年09月20日, 日本語, 口頭発表（一般）
2021年09月20日 - 2021年09月23日

Proposal of new-type vortex Airy beam with improved propagation characteristics
Masato Suzuki, Keisaku Yamane, Takashige Omatsu, Ryuji Morita
JSAP-OSA Joint Symposia 2021, 2021年08月26日, 英語, 口頭発表（一般）
2021年08月26日 - 2021年08月26日

光渦の軌道角運動量分解精度向上のための偏光回折素子光学系開発　　　　　　　　　　　　　　　
飯塚 健介, 山根 啓作, 川村 一貴, 坂本 盛嗣, 小野 浩司, 岡 和彦, 戸田 泰則, 森田 隆二
第６８回応用物理学会春季学術講演会, 2021年03月16日, 口頭発表（一般）
2021年03月16日 - 2021年03月19日

偏光回折素子を用いた光波複製による軌道角運動量分解精度の向上　　　　　　　　　　　　　　　
飯塚 健介, 山根 啓作, 坂本 盛嗣, 小野 浩司, 岡 和彦, 本田 亜沙美, 鈴木 雅人, 戸田 泰則, 森田 隆二
レーザー学会 第41回年次大会, 2021年01月18日, 日本語, 口頭発表（一般）
2021年01月18日 - 2021年01月20日

光学渦による六方最密充填フォトニックリングの生成　　　　　　　　　　　　　　　
TAKAHASHI Kanta, KAWAGUCHI Haruki, UMESATO Kei, ARITA Yoshihiko, ARITA Yoshihiko, YAMANE Keisaku, MORITA Ryuji, YUYAMA Ken-ichi, KAWANO Satoyuki, MIYAMOTO Katsuhiko, OMATSU Takashige
International Conference on Simulation Technology (CD-ROM), 2021年
2021年 - 2021年

単一八面体Auナノ粒子の光渦誘起前方移動【JST・京大機械翻訳】　　　　　　　　　　　　　　　
KAWAGUCHI Haruki, WEI Rong, YAMANE Keisaku, MORITA Ryuji, YUYAMA Ken-ichi, KAWANO Satoyuki, MIYAMOTO Katsuhiko, TORIMOTO Tsukasa, OMATSU Takashige
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2021年
2021年 - 2021年

光渦誘起六方晶密充填フォトニックマイクロリング【JST・京大機械翻訳】　　　　　　　　　　　　　　　
TAKAHASHI Kanta, KAWAGUCHI Haruki, UMESATO Kei, ARITA Yoshihiko, ARITA Yoshihiko, YAMANE Keisaku, MORITA Ryuji, YUYAMA Ken-ichi, KAWANO Satoyuki, MIYAMOTO Katsuhiko, OMATSU Takashige
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2021年
2021年 - 2021年

光渦レーザー誘起前方転写法を用いた金ナノインクプリンティング　　　　　　　　　　　　　　　
川口晴生, 梅里慧, 高橋幹太, 山根啓作, 柚山健一, 川野聡恭, 森田隆二, 宮本克彦, 宮本克彦, 尾松孝茂, 尾松孝茂
Optics & Photonics Japan講演予稿集(CD-ROM), 2021年, 日本語, 口頭発表（一般）
2021年 - 2021年

オンラインプログラミング環境を使った実験教育の試み　　　　　　　　　　　　　　　
友田基信, 山崎憲慈, 柏本史郎, 田中之博, 佐々木裕司, 山根啓作
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2021年, 日本語, 口頭発表（一般）
2021年 - 2021年

光渦レーザー誘起前方転写法による超解像金属ナノ微粒子パターニング　　　　　　　　　　　　　　　
川口晴生, 梅里慧, 高橋幹太, 柚山健一, 山根啓作, 宮本克彦, 尾松孝茂
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2021年, 日本語, 口頭発表（一般）
2021年 - 2021年

カイラル変調分光を目的とする分割型デフォーマブルミラーを用いた光渦生成　　　　　　　　　　　　　　　
下田隆一, 土屋聡, 山根啓作, 森田隆二, 戸田泰則
応用物理学会北海道支部/日本光学会北海道支部合同学術講演会講演予稿集, 2021年
2021年 - 2021年

空間変調光帰還型面発光レーザーのOAMモード発振制御　　　　　　　　　　　　　　　
仲川幸輝, 山根啓作, 森田隆二, 戸田泰則
応用物理学会北海道支部/日本光学会北海道支部合同学術講演会講演予稿集, 2021年
2021年 - 2021年

Ultrafast azimuth rotation of linearly polarized beam by use of a chirped optical pulse pair
Rin Sasaki, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda, Takashige Omatsu, Ryuji Morita
Optical Manipulation and Structured Materials Conference (OMC 2020), 2020年04月23日, SPIE-INT SOC OPTICAL ENGINEERING, 英語, 口頭発表（一般）
2020年04月20日 - 2020年04月23日, We demonstrated that ultrafast azimuth rotation of linearly polarized beam by use of a chirped optical pulse pair, and the rotational frequency of sub-THz was realized.

偏光回折素子を用いた高精度OAMモード分解光学系の検討　　　　　　　　　　　　　　　
渡辺悠歩, 山根啓作, 坂本盛嗣, 小野浩司, 岡和彦, 戸田泰則, 森田隆二
第67回応用物理学会春季学術講演会, 2020年03月13日, 日本語, 口頭発表（一般）
2020年03月12日 - 2020年03月15日

高次横モード光励起を用いた面発光レーザーの光渦発振特性　　　　　　　　　　　　　　　
仲川幸輝, 山根啓作, 森田隆二, 戸田泰則
応用物理学会北海道支部/日本光学会北海道支部合同学術講演会講演予稿集, 2020年
2020年 - 2020年

ガラス上のレーザー誘起表面周期構造形成のための繰り返し周波数可変超短光パルスファイバーレーザーの構築　　　　　　　　　　　　　　　
辻亮, 山根啓作, 望月克, 戸田泰則, 森田隆二
応用物理学会北海道支部/日本光学会北海道支部合同学術講演会講演予稿集, 2020年
2020年 - 2020年

時空間制御光波発生のための高繰り返しファイバーレーザーの構築
島谷航平, 山根啓作, 戸田泰則, 森田隆二
応用物理学会北海道支部/日本光学会北海道支部合同学術講演会講演予稿集, 2019年01月05日, 日本語
2019年01月05日 - 2019年01月05日

二光子吸収誘起表面レリーフ形成過程におけるスピン軌道相互作用　　　　　　　　　　　　　　　
篠崎諒, 増田圭吾, 杵塚義典, 一條瑞樹, 倉元佑樹, 山根啓作, 宮本克彦, 宮本克彦, 尾松孝茂, 尾松孝茂
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2019年
2019年 - 2019年

OAMモード分解精度向上のための低損失ビーム整形素子の開発　　　　　　　　　　　　　　　
渡辺悠歩, 山根啓作, 岡和彦, 戸田泰則, 森田隆二
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2019年
2019年 - 2019年

高効率な時空間制御光波発生装置の開発　　　　　　　　　　　　　　　
岩佐康平, 佐々木凜, 山根啓作, 岡和彦, 戸田泰則, 森田隆二
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2019年
2019年 - 2019年

光渦の二光子吸収によって形成されたキラル表面レリーフ　　　　　　　　　　　　　　　
篠崎諒, 増田圭吾, 一條瑞樹, 山根啓作, 宮本克彦, 宮本克彦, 尾松孝茂, 尾松孝茂
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2019年
2019年 - 2019年

空間変調光帰還型面発光レーザーのOAMモード偏光特性　　　　　　　　　　　　　　　
仲川幸輝, 山根啓作, 森田隆二, 戸田泰則
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2019年
2019年 - 2019年

光波の幾何学的変換に基づく光渦の軌道角運動量分解における強度歪み補正
脇坂勇武, 渡辺悠歩, 山根啓作, 岡和彦, 戸田泰則, 森田隆二
Optics & Photonics Japan講演予稿集(CD-ROM), 2018年10月24日, 日本語
2018年10月24日 - 2018年10月24日

チャネルドスペクトルによる分光偏光計
岡和彦, 坂本盛嗣, 山根啓作, 森田隆二
精密工学会大会学術講演会講演論文集, 2018年09月05日, 日本語
2018年09月05日 - 2018年09月05日

チャープパルス対を利用した直線偏光の偏光方位のsub‐THz域超高速回転
佐々木凜, 岩佐康平, 山根啓作, 岡和彦, 戸田泰則, 森田隆二
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2018年09月05日, 日本語
2018年09月05日 - 2018年09月05日

光渦の軌道角運動量分解精度向上のための光波複製光学系の開発
渡辺悠歩, 山根啓作, 岡和彦, 戸田泰則, 森田隆二
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2018年09月05日, 日本語
2018年09月05日 - 2018年09月05日

光波の幾何学的変換を利用したOAM分解素子の開発
山根啓作, 脇坂勇武, 渡辺悠歩, 岡和彦, 戸田泰則, 森田隆二
電子情報通信学会技術研究報告, 2018年07月05日, 日本語
2018年07月05日 - 2018年07月05日

光渦・偏光渦を使った窒化ガリウム励起子のコヒーレント分光
戸田泰則, 重松恭平, 山根啓作, 森田隆二
レーザー研究, 2018年04月20日, 日本語
2018年04月20日 - 2018年04月20日

偏光における幾何学的位相を利用した軌道角運動量分解素子の開発
山根啓作, 渡辺悠歩, 岡和彦, 戸田泰則, 森田隆二
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2018年03月05日, 日本語
2018年03月05日 - 2018年03月05日

自己参照型干渉法を用いた光渦の小型軌道角運動量分解装置の構築
住吉祥伍, 山根啓作, 戸田泰則, 森田隆二
応用物理学会北海道支部/日本光学会北海道支部合同学術講演会講演予稿集, 2018年01月06日, 日本語
2018年01月06日 - 2018年01月06日

光渦により公転運動させたミクロ粒子の回転ドップラー計測
坪谷春輝, 司馬哲裕, 山根啓作, 戸田泰則, 森田隆二
応用物理学会北海道支部/日本光学会北海道支部合同学術講演会講演予稿集, 2018年01月06日, 日本語
2018年01月06日 - 2018年01月06日

ポアンカレビームパルスを用いたGaN励起子の四光波混合分光
内古閑隆太郎, 山根啓作, 森田隆二, 戸田泰則
応用物理学会北海道支部/日本光学会北海道支部合同学術講演会講演予稿集, 2018年01月06日, 日本語
2018年01月06日 - 2018年01月06日

時空間領域における光波制御技術
山根啓作, 森田隆二
Optics & Photonics Japan講演予稿集(CD-ROM), 2017年10月16日, 日本語
2017年10月16日 - 2017年10月16日

トポロジカル光波の発生・計測技術
山根啓作
電子情報通信学会大会講演論文集(CD-ROM), 2017年08月29日, 日本語
2017年08月29日 - 2017年08月29日

光渦パルス励起による超伝導準粒子軌道角運動量ダイナミクス観測
望月洋人, 戸田泰則, 土屋聡, 山根啓作, 森田隆二, 黒沢徹, 小田研
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2017年08月25日, 日本語
2017年08月25日 - 2017年08月25日

空間変調光帰還型面発光レーザーのOAMモード発振特性
森谷淳史, 戸田泰則, 山根啓作, 森田隆二, 重松恭平, 淡路祥成
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2017年08月25日, 日本語
2017年08月25日 - 2017年08月25日

sub‐mJ級超高速回転リング状光格子の発生
岩佐康平, 柿澤康平, 山根啓作, 岡和彦, 戸田泰則, 森田隆二
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2017年08月25日, 日本語
2017年08月25日 - 2017年08月25日

高強度・超高速回転リング状光格子の発生
柿澤康平, 岩佐康平, 山根啓作, 岡和彦, 戸田泰則, 森田隆二
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2017年03月01日, 日本語

幾何学的変換に基づく光渦の高精度軌道角運動量分解計測
山根啓作, 戸田泰則, 森田隆二
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2017年03月01日, 日本語

軸対称偏光素子を用いたトラップ粒子の回転制御(II)
小原威吹, 坂本盛嗣, 山根啓作, 森田隆二, 岡和彦
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2017年03月01日, 日本語

光渦の干渉パターンを用いた微小粒子の回転制御
小原威吹, 坂本盛嗣, 山根啓作, 森田隆二, 岡和彦
応用物理学会北海道支部・日本光学会北海道地区合同学術講演会講演予稿集, 2017年01月07日, 日本語

Single orbital angular momentum mode emission from vertical cavity surface emitting laser by optical feedback
Y. Toda, H. Moriya, K. Shigematsu, K. Yamane, R. Morita, Y. Awaji
Proceedings of SPIE - The International Society for Optical Engineering, 2017年01月01日
© 2017 SPIE. Single angular momentum (OAM) mode emissions from a vertical cavity surface emitting laser (VCSEL) were demonstrated by an external optical feedback using computer generated holograms, which are optimized on the OAM modal gain of the free-running VCSEL. Side-mode suppression ratio of more than 23 dB was achieved for the OAM modes with ℓ = ±1.

Generation of intense ultrafast-rotating ring-shaped optical lattices with programmable control of rotational symmetry
Keisaku Yamane, Kohei Iwasa, Kohei Kakizawa, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
Proceedings of SPIE - The International Society for Optical Engineering, 2017年01月01日
© 2017 SPIE. A new method for the ultrafast rotation of ring-shaped optical lattices based on frequency-chirping of optical pulses was demonstrated in THz regime, which is three orders of magnitude faster than those by the conventional methods. Our optical lattice generator with a spatial light modulator is robust thanks to the 4-f configuration and enables us to flexibly control their rotational symmetry. The generated ultrafast-rotating ring-shaped optical lattices with a rotational frequency of 0.59 THz were successfully boosted from 5 μJ up to 125 μJ by using a home-built 4-pass Ti:sapphire amplifier without any limitation by optical damage to the spatial light modulator.

ポアンカレビームパルスを用いたGaN励起子スピンのコヒーレントダイナミクス観測
内古閑隆太郎, 重松恭平, 山根啓作, 森田隆二, 戸田泰則
日本物理学会講演概要集(CD-ROM), 2016年09月23日, 日本語

光渦パルスのチャープ特性を利用したプログラマブル超高速回転リング状光格子の生成
柿澤康平, 山根啓作, 岡和彦, 戸田泰則, 森田隆二
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2016年09月01日, 日本語

空間変調光注入同期による面発光レーザーのトポロジカルチャージ制御
西坂拓馬, 重松恭平, 山根啓作, 山根啓作, 森田隆二, 森田隆二, 淡路祥成, 戸田泰則, 戸田泰則
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2016年03月03日, 日本語

軸対称偏光子を用いたトラップ粒子の回転制御
小原威吹, 坂本盛嗣, 山根啓作, 森田隆二, 岡和彦
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2016年03月03日, 日本語

チャープパルスを用いた直線偏光の偏光方位の超高速回転
永井美祐, 坂本盛嗣, 坂本盛嗣, 山根啓作, 森田隆二, 岡和彦
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2016年03月03日, 日本語

光渦によって形成される単結晶性シリコンニードルのパルス幅依存性
藤原穂波, 高橋冬都, 泉澤魁, 比田井洋史, 宮本克彦, 山根啓作, 森田隆二, 尾松孝茂
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2016年03月03日, 日本語

拡張ストークスパラメータにおける拡張偏光度スペクトルを用いた光波の空間回転対称性解析の検討
鈴木雅人, 山根啓作, 岡和彦, 戸田泰則, 森田隆二
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2016年03月03日, 日本語

時空間分解偏光解析から明らかとなった励起子コヒーレントダイナミクスにおける回転対称性破れ
重松恭平, 鈴木雅人, 山根啓作, 森田隆二, 戸田泰則
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2016年03月03日, 日本語

Comment on "Higher Order Pancharatnam-Berry Phase and the Angular Momentum of Light"
Masato Suzuki, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
2016年02月08日
2016年02月08日 - 2016年02月08日, In a recent letter, Milione et al. reported the Pancharatnam-Berry phase

(PBP) on a higher-order Poincar\'e sphere (HOPS) [Phys. Rev. Lett, 108, 190401

(2012)]. They used two spin-orbit converters (SOCs) to make a trajectory along

the HOPS. However, the SOCs actually do not make a path on the HOPS. We briefly

discuss a way of acquiring a PBP made by SOCs.

空間変調光帰還による面発光レーザーのラゲールガウスモード制御
西坂拓馬, 重松恭平, 由利洋樹, 山根啓作, 山根啓作, 森田隆二, 森田隆二, 淡路祥成, 戸田泰則, 戸田泰則
応用物理学会北海道支部・日本光学会北海道地区合同学術講演会講演予稿集, 2016年01月09日, 日本語
2016年01月09日 - 2016年01月09日

パルス幅可変光渦を用いたナノニードル形成とそのメカニズムに関する研究
里水里, 山根啓作, 山根啓作, 戸田泰則, 戸田泰則, 森田隆二, 森田隆二
応用物理学会北海道支部・日本光学会北海道地区合同学術講演会講演予稿集, 2016年01月09日, 日本語

超微細加工のための高強度・高繰り返しYb:YAG超短光パルスレーザーの構築
角田恵一郎, 山根啓作, 山根啓作, 戸田泰則, 戸田泰則, 森田隆二, 森田隆二
応用物理学会北海道支部・日本光学会北海道地区合同学術講演会講演予稿集, 2016年01月09日, 日本語

Quantitative characterization of polarization states of axisymmetrically polarized pulses generated by coherent beam combining
Masato Suzuki, Keisaku Yamane, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda, Yasunori Toda, Ryuji Morita, Ryuji Morita
Conference on Lasers and Electro-Optics Europe - Technical Digest, 2015年08月10日
© 2015 OSA.By using the extended Stokes parameters and the degree of polarization defined for the spatial distribution (DOP-SD), we fully quantitatively characterize the polarization states of arbitrary (DOP-SD>0.96) axisymmetrically-polarized femtosecond pulses generated by coherent beam combining.

21pCP-4 軸対称偏光パルスを用いたGaN励起子微細構造の四光波混合分光
重松 恭平, 森本 祥平, 鈴木 雅人, 山根 啓作, 森田 隆二, 戸田 泰則
日本物理学会講演概要集, 2015年03月21日, 日本語

21pCP-4 軸対称偏光パルスを用いたGaN励起子微細構造の四光波混合分光
重松 恭平, 森本 祥平, 鈴木 雅人, 山根 啓作, 森田 隆二, 戸田 泰則
日本物理学会講演概要集, 2015年, 日本語

Quantitative characterization of polarization states of axisymmetrically polarized pulses generated by coherent beam combining
Masato Suzuki, Keisaku Yamane, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda, Yasunori Toda, Ryuji Morita, Ryuji Morita
CLEO: Science and Innovations, CLEO-SI 2015, 2015年01月01日
By using the extended Stokes parameters and the degree of polarization defined for the spatial distribution (DOP-SD), we fully quantitatively characterize the polarization states of arbitrary (DOP-SD>0.96) axisymmetrically-polarized femtosecond pulses generated by coherent beam combining. © 2014 Optical Society of America.

Fractional optical vortex parametric oscillator
YUSUFU Taximaiti, ABULIKEMU Aizitiaili, YAMANE Keisaku, MIYAMOTO Katsuhiko, OMATSU Takashige
Optics & Photonics Japan講演予稿集(CD-ROM), 2014年10月24日, 英語

Eigenmode expansion of optical vortices based on electric-field reconstruction in spatial domain
Keisaku Yamane, Keisaku Yamane, Shota Nakajima, Masato Suzuki, Masato Suzuki, Yasunori Toda, Yasunori Toda, Ryuji Morita, Ryuji Morita
Optics InfoBase Conference Papers, 2014年07月21日

Quantitative analysis of l = 2 radially polarized ultrashort pulses by using extended stokes parameters
Masato Suzuki, Keisaku Yamane, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda, Yasunori Toda, Ryuji Morita, Ryuji Morita
Optics InfoBase Conference Papers, 2014年07月21日

Coherent dynamics of uniaxially-strained GaN excitons excited by cylindrically polarized pulses
K. Shigematsu, S. Morimoto, M. Suzuki, K. Yamane, K. Yamane, R. Morita, R. Morita, Y. Toda, Y. Toda
Optics InfoBase Conference Papers, 2014年07月21日

Generation of the ring-shaped optical lattice using axially-symmetric polarization elements (II)
Moritsugu Sakamoto, Keisaku Yamane, Keisaku Yamane, Naoshi Murakami, Ryuji Morita, Ryuji Morita, Kazuhiko Oka
Frontiers in Optics, FiO 2014, 2014年01月01日
© 2014 Optical Society of America.A novel optical system of a ring-shaped optical-lattice generator using axially-symmetric polarization elements is presented. A series of axially-symmetric polarization elements incorporated into the configuration enables generating any combination of vortices with even-numbered topolog-ical charges.

Generation of ultra-broadband pulses with axially-symmetric polarization based on coherent beam combining of optical vortices
Keisaku Yamane, Yasuyuki Shioda, Masato Suzuki, Yasunori Toda, Ryuji Morita
Conference on Lasers and Electro-Optics Europe - Technical Digest, 2014年01月01日
© 2014 Optical Society of America.We demonstrated the generation of ultra-broadband optical pulses with axiallysymmetric polarization, on the basis of a coherent beam combining technique. The high polarization purity (∼95 %) ranging from 750 to 880 nm was obtained.

Generation of ultra-broadband pulses with axially-symmetric polarization based on coherent beam combining of optical vortices
Keisaku Yamane, Yasuyuki Shioda, Masato Suzuki, Yasunori Toda, Ryuji Morita
Optics InfoBase Conference Papers, 2014年01月01日
We demonstrated the generation of ultra-broadband optical pulses with axiallysymmetric polarization, on the basis of a coherent beam combining technique. The high polarization purity (~95 %) ranging from 750 to 880 nm was obtained. © 2014 Optical Society of America.

Spatiotemporal coherence of GaN excitons excited by an optical vortex with multiple orbital angular momentum
Kyohhei Shigematsu, Keisaku Yamane, Keisaku Yamane, Ryuji Morita, Ryuji Morita, Yasunori Toda, Yasunori Toda
Optics InfoBase Conference Papers, 2014年01月01日
The spatiotemporal coherence of excitons is investigated by degenerate four-wavemixing using optical vortices with multiple orbital angular momentum (OAM). The OAMresolved signal indicates that the topological phase with large OAM is robust against spatial decoherence. © 2014 OSA.

Ultrafast and ultra-broadband optical-vortex pulse generation and characterization
Ryuji Morita, Ryuji Morita, Keisaku Yamane, Keisaku Yamane, Zhili Yang, Yasunori Toda, Yasunori Toda
Proceedings of SPIE - The International Society for Optical Engineering, 2014年01月01日
Subsequently to the previous generation of ultrashort and ultra-broadband optical-vortex (OV) pulses (pulse energy: several tens of μJ) in few-cycle regime, we demonstrate high-power OV pulse generation with topological charge flexibility by employing a 4-f OV converter and pre- and main-amplifications. Our configuration overcomes the low-throughput drawback of the vortex converter, simultaneously compensating for the angular dispersion. It also gives flexibility of OAMor topological-charge control. Thus, we succeed in generation of mJ-class ultra-broadband OV pulses (∼790-∼820 nm) with a programmably-controlled topological charge. Moreover, we experimentally exhibit a high-precision method for measuring frequency-resolved OAM spectrum of femtosecond ultra-broadband OV pulses on the basis of electric-field reconstruction in the spatial domain. In addition, we present the generation of ultrashort pulses with axially-symmetric polarization by coherent beam combining of OVs.

Over 1-mJ intense ultrashort optical-vortex pulse generation with programmable topological-charge control by chirped-pulse amplification
Keisaku Yamane, Asami Honda, Yasunori Toda, Ryuji Morita
Optics InfoBase Conference Papers, 2014年01月01日
We demonstrated the generation of over 1-mJ intense optical-vortex pulses of which topological charges were programmably controlled by computer-generated holograms. The pulse duration was characterized to be 27 fs by two-dimensional spectral shearing interferometry. © 2014 OSA.

Spatiotemporal coherence of GaN excitons excited by an optical vortex with multiple orbital angular momentum
Kyohhei Shigematsu, Keisaku Yamane, Keisaku Yamane, Ryuji Morita, Ryuji Morita, Yasunori Toda, Yasunori Toda
Conference on Lasers and Electro-Optics Europe - Technical Digest, 2014年01月01日
© 2014 Optical Society of America.The spatiotemporal coherence of excitons is investigated by degenerate four-wavemixing using optical vortices with multiple orbital angular momentum (OAM). The OAMresolved signal indicates that the topological phase with large OAM is robust against spatial decoherence.

Nonlinear conversion between ultrashort radially-and azimuthally-polarized pulses in an anisotropic media
Masato Suzuki, Keisaku Yamane, Keisaku Yamane, Yasunori Toda, Yasunori Toda, Ryuji Morita, Ryuji Morita
Optics InfoBase Conference Papers, 2013年12月01日

Amplification of ultrashort optical-vortex pulses with programmable topological-charge control
Keisaku Yamane, Yasunori Toda, Ryuji Morita
CLEO: QELS_Fundamental Science, CLEO:QELS FS 2013, 2013年11月21日
We demonstrate the amplification of ultrashort optical-vortex pulses through the optical parametric process, where optical-vortex seed pulses with computer-controlled topological charges are employed. In this scheme, the low-throughput drawback of the vortex converter is overcome. © 2013 Optical Society of America.

Quasi-real-time measurement of orbital angular momentum spectra of ultra-broadband optical vortices from fork-like interferograms
Zhili Yang, Keisaku Yamane, Yasunori Toda, Ryuji Morita
CLEO: QELS_Fundamental Science, CLEO:QELS FS 2013, 2013年11月21日
We experimentally demonstrate a simple and high-precision method for measuring orbital angular momentum (OAM) spectra of femtosecond ultra-broadband optical-vortex pulses from fork-like interferograms. This method enables quasi-real-time OAM measurement for ultrashort or ultra-broadband optical vortices. © OSA 2013.

Amplification of ultrashort optical-vortex pulses with programmable topological-charge control
Keisaku Yamane, Yasunori Toda, Ryuji Morita
CLEO: Applications and Technology, CLEO_AT 2013, 2013年11月19日
We demonstrate the amplification of ultrashort optical-vortex pulses through the optical parametric process, where optical-vortex seed pulses with computer-controlled topological charges are employed. In this scheme, the low-throughput drawback of the vortex converter is overcome. © 2013 Optical Society of America.

Amplification of ultrashort optical-vortex pulses with programmable topological-charge control
Keisaku Yamane, Yasunori Toda, Ryuji Morita
CLEO: Science and Innovations, CLEO_SI 2013, 2013年11月18日
We demonstrate the amplification of ultrashort optical-vortex pulses through the optical parametric process, where optical-vortex seed pulses with computer-controlled topological charges are employed. In this scheme, the low-throughput drawback of the vortex converter is overcome. © 2013 Optical Society of America.

Programmable ultrashort optical-vortex pulse generation using optical parametric amplification and 4-f configuration
Keisaku Yamane, Asami Honda, Kyohhei Shigematsu, Yasunori Toda, Ryuji Morita
Pacific Rim Conference on Lasers and Electro-Optics, CLEO - Technical Digest, 2013年10月18日
We demonstrate the optical parametric amplification of optical-vortex pulses with the programmable topological-charge control. Combination of optical-parametric amplification and 4-f configuration overcomes the low-throughput drawback of the vortex converter, simultaneously compensating for the angular dispersion. © 2013 IEEE.

Nonlinear coupling between radially-and azimuthally-polarized modes of ultrashort optical pulses in an anisotropic crystal
Masato Suzuki, Keisaku Yamane, Keisaku Yamane, Yasunori Toda, Yasunori Toda, Ryuji Morita, Ryuji Morita
Pacific Rim Conference on Lasers and Electro-Optics, CLEO - Technical Digest, 2013年10月18日
We investigate nonlinear propagation of ultrashort optical pulses with radially-and azimuthally-polarized modes in a uniaxial crystal. The energy exchange between the modes, ascribed to nonlinear four-wave-mixing effect with Gouy-phase shifts, is discussed. © 2013 IEEE.

28aDB-12 複合光渦励起による励起子軌道角運動量スペクトルダイナミクス(励起子・ポラリトン,領域5(光物性))
重松 恭平, 戸田 泰則, 山根 啓作, 森田 隆二
日本物理学会講演概要集, 2013年08月26日, 日本語

Frequency-resolved Orbital Angular Momentum Spectrum Measurement of Ultra-broadband Optical Vortices　　　　　　　　　　　　　　　
2013 CONFERENCE ON LASERS AND ELECTRO-OPTICS PACIFIC RIM (CLEO-PR), 2013年

Amplification of ultrashort optical-vortex pulses with programmable topological-charge control
Keisaku Yamane, Yasunori Toda, Ryuji Morita
2013 Conference on Lasers and Electro-Optics, CLEO 2013, 2013年01月01日
We demonstrate the amplification of ultrashort optical-vortex pulses through the optical parametric process, where optical-vortex seed pulses with computer-controlled topological charges are employed. In this scheme, the low-throughput drawback of the vortex converter is overcome. © 2013 The Optical Society.

Nonlinear conversion between ultrashort radially- and azimuthally-polarized pulses in an anisotropic media
Masato Suzuki, Keisaku Yamane, Keisaku Yamane, Yasunori Toda, Yasunori Toda, Ryuji Morita, Ryuji Morita
2013 Conference on Lasers and Electro-Optics Europe and International Quantum Electronics Conference, CLEO/Europe-IQEC 2013, 2013年01月01日
A radially- or azimuthally-polarized mode is one of the axially-polarized modes, changing its local polarization state as a function of the azimuthal angle. It can be expressed by a superposition of the left-circularly polarized (LCP; s = +1: spin angular momentum (SAM) of light) l= - 1 optical vortex and the right-circularly polarized (RCP;s= - 1) l = + 1 optical vortex. Here, the term optical vortex simply refers to a Laguerre-Gaussian mode with a zero-radial index. l is an orbital angular momentum (OAM) of light per photon in h ̄ units which causes the phase ramp around the phase singular point [1]. In a beam propagating along the optic axis of a uniaxial crystal, the crystal anisotropy induces its SAM conversion between s = +1 and s = - 1 states under the conservation of total angular momentum s +l. Thus, a uniaxial crystal is used for high-power generation of s= - 1, l = 2 optical vortex pulses from Gaussian beam pulses (s=+1, l = 0) [2] , or enables us to separate radially- or azimuthally-polarized pulses froms = ±1, l = =±1 optical vortex pulses [3]. This method using a uniaxial crystal is suited for high power pulse generation because the threshold value is higher than those in other methods using a spiral plate [3] , a spatial light modulator (SLM) [4] or a photonic-crystal axially-symmetric polarizer/waveplate [5] . However, earlier studies [2,3] avoid nonlinear effects by inputting a diverging beam into a uniaxial crystal and hence the nonlinear effects, such as Kerr or four-wave-mixing effects between radially- and azimuthally-polarized modes, have not been well investigated. In the present paper, we experimentally investigate optical-vortex pulse propagation in a uniaxial crystal through nonlinear converting between radially- and azimuthally-polarized pulses. © 2013 IEEE.

Quasi-real-time measurement of orbital angular momentum spectra of ultra-broadband optical vortices from fork-like interferograms
Zhili Yang, Keisaku Yamane, Yasunori Toda, Ryuji Morita
2013 Conference on Lasers and Electro-Optics, CLEO 2013, 2013年01月01日
We experimentally demonstrate a simple and high-precision method for measuring orbital angular momentum (OAM) spectra of femtosecond ultra-broadband optical-vortex pulses from fork-like interferograms. This method enables quasi-real-time OAM measurement for ultrashort or ultra-broadband optical vortices. © 2013 The Optical Society.

非線型屈折率効果を伴う物質の異方性を用いた光子のスピン軌道角運動量変換 III
鈴木雅人, 山根啓作, 戸田泰則, 戸田泰則, 森田隆二, 森田隆二
応用物理学会学術講演会講演予稿集(CD-ROM), 2012年08月27日, 日本語

高次光渦励起によるGaN励起子の軌道角運動量分解四光波混合分光
重松恭平, 戸田泰則, 戸田泰則, 山根啓作, 山根啓作, 森田隆二, 森田隆二
応用物理学会学術講演会講演予稿集(CD-ROM), 2012年08月27日, 日本語

Measurement of orbital angular momentum spectrum from fork-like interferogram
ZHILI Yang, YAMANE Keisaku, TODA Yasunori, MORITA Ryuji
応用物理学会学術講演会講演予稿集(CD-ROM), 2012年08月27日, 英語

数サイクル域超短光渦パルス発生
山根啓作, 戸田泰則, 森田隆二
応用物理学関係連合講演会講演予稿集(CD-ROM), 2012年02月29日, 日本語

非線型屈折率効果を伴う物質の異方性を用いた光子のスピン軌道角運動量変換 II
鈴木雅人, 山根啓作, 戸田泰則, 戸田泰則, 森田隆二, 森田隆二
応用物理学会学術講演会講演予稿集(CD-ROM), 2011年08月16日, 日本語

Complete characterization of single attosecond pulses by the modified spectral phase interferometry with an all-optical apparatus
J. Zhu, S. Fang, T. Chen, K. Yamane, M. Yamashita
Optics InfoBase Conference Papers, 2010年12月01日
We present the complete characterization of single attosecond pulses by the modified SPIDER method with a frequency-dependent spectral shear. The validity of this method shows no principle limitation of characterizing arbitrary short single attosecond pulses. © 2010 Optical Society of America.

The development of angularly-dispersed non-collinear optical parametric amplifier for generation of high power optical pulses in monocycle regime
Keisaku Yamane, Takashi Tanigawa, Taro Sekikawa, Mikio Yamashita
Optics InfoBase Conference Papers, 2010年12月01日
We greatly improved our angularly-dispersed NOPA system and introduced a new stretcher for seed pulses. Consequently, we achieved the broadest gain bandwidth ranging from 500 to 1030 nm with output pulse energy of 45 μJ. © OSA / UP 2010.

Ultra-broadband spectral-shifted pulse pair generation by amplitude modulation for single attosecond pulse characterization using the SPIDER method
J. Zhu, T. Tanigawa, T. Chen, S. Fang, K. Yamane, M. Yamashita
Optics InfoBase Conference Papers, 2010年12月01日
Ultra-broadband amplitude modulation for spectral-shifted pulse pair generation is realized by a liquid-crystal spatial light modulator. The results indicate that it's a promising way for single attosecond pulse characterization by the conventional SPIDER method. © 2010 Optical Society of America.

Complete characterization of single attosecond pulses by the modified spectral phase interferometry with an all-optical apparatus
J. Zhu, S. Fang, T. Chen, K. Yamane, M. Yamashita
Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference: 2010 Laser Science to Photonic Applications, CLEO/QELS 2010, 2010年10月11日
We present the complete characterization of single attosecond pulses by the modified SPIDER method with a frequency-dependent spectral shear. The validity of this method shows no principle limitation of characterizing arbitrary short single attosecond pulses. © 2010 Optical Society of America.

Ultra-broadband spectral-shifted pulse pair generation by amplitude modulation for single attosecond pulse characterization using the SPIDER method
J. Zhu, T. Tanigawa, T. Chen, S. Fang, K. Yamane, M. Yamashita
Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference: 2010 Laser Science to Photonic Applications, CLEO/QELS 2010, 2010年10月11日
Ultra-broadband amplitude modulation for spectral-shifted pulse pair generation is realized by a liquid-crystal spatial light modulator. The results indicate that it's a promising way for single attosecond pulse characterization by the conventional SPIDER method. © 2010 Optical. Society of America.

角度分散型NOPAによる高出力オーバーオクターブ光パルス発生
山根啓作, 谷川崇, 関川太郎, 山下幹雄
応用物理学会学術講演会講演予稿集(CD-ROM), 2010年08月30日, 日本語

角度分散型NOPAによる高出力極短光パルス発生
山根啓作, 谷川崇, 関川太郎, 山下幹雄
応用物理学関係連合講演会講演予稿集(CD-ROM), 2010年03月03日, 日本語

2光子吸収下での非同軸光パラメトリック増幅の最適設計
谷川崇, 山根啓作, 唐澤直樹, 山下幹雄
応用物理学関係連合講演会講演予稿集(CD-ROM), 2010年03月03日, 日本語

高出力モノサイクルパルス発生へ向けた角度分散型NOPA装置開発
山根啓作, 山根啓作, 谷川崇, 谷川崇, 関川太郎, 関川太郎, 山下幹雄, 山下幹雄
応用物理学会学術講演会講演予稿集, 2009年09月08日, 日本語

Ti:sapphireレーザー第3高調波励起による400nm域非同軸光パラメトリック増幅の数値解析
谷川崇, 谷川崇, 山根啓作, 山根啓作, 唐澤直樹, 関川太郎, 関川太郎, 山下幹雄, 山下幹雄
応用物理学会学術講演会講演予稿集, 2009年09月08日, 日本語

マルチオクターブ光スペクトル位相計測のための2DSI装置開発
片寄慎斗, 山根啓作, 関川太郎, 山下幹雄
応用物理学関係連合講演会講演予稿集, 2009年03月30日, 日本語

Monocycle pulse generation and octave bandwidth amplification　　　　　　　　　　　　　　　
2009 LASERS & ELECTRO-OPTICS & THE PACIFIC RIM CONFERENCE ON LASERS AND ELECTRO-OPTICS, VOLS 1 AND 2, 2009年

Nearly-octave broadband, high-powered optical parametric amplification toward monocycle regime
Keisaku Yamane, Takashi Tanigawa, Taro Sekikawa, Mikio Yamashita
2008 Conference on Quantum Electronics and Laser Science Conference on Lasers and Electro-Optics, CLEO/QELS, 2008年09月15日
We demonstrated the generation of 34-μJ, 14-fs optical pulses with an ultrabroad bandwidth (540 - 1000 nm) by the use of one angularly-dispersed non-collinear optical parametric amplifier. © 2007 Optical Society of America.

Nearly-octave broadband, high-powered optical parametric amplification toward monocycle regime
Keisaku Yamane, Takashi Tanigawa, Taro Sekikawa, Mikio Yamashita
Optics InfoBase Conference Papers, 2008年01月01日
We demonstrated the generation of 34-μJ, 14-fs optical pulses with an ultrabroad bandwidth (540-1000 nm) by the use of one angularly-dispersed non-collinear optical parametric amplifier. © 2007 Optical Society of America.

Efficient compression of carrier-envelope phase-locked laser pulses to 5 fs using an aluminum-coated hollow fiber
Eisuke Haraguchi, Takashi Tanigawa, Eiichi Matsubara, Keisaku Yamane, Mikio Yamashita, Taro Sekikawa
Conference on Lasers and Electro-Optics, 2007, CLEO 2007, 2007年12月01日
Carrier-envelope phase-lacked 0.13-TW, 5.2-fs laser pulses were generated by using a 56-cm-long aluminum-coated hollow fiber with an efficiency of 66 %, improved by coating aluminum inside the fiber with a core diameter of 500-μm. © 2007 Optical Society of America.

Optical parametric amplification of optical pulses with a nearly one-octave bandwidth from a hollow fiber
K. Yamane, A. Iwasaki, T. Tanigawa, T. Sekikawa, M. Yamashita
Conference on Lasers and Electro-Optics, 2007, CLEO 2007, 2007年12月01日
We developed an angularly dispersed noncollinear optical parametric amplifier with a 300-THz bandwidth (550 - 1000 nm) for the first time. To the best of our knowledge, this is the broadest parametric gain. © 2006 Optical Society of America.

Optical parametric amplification of optical pulses with a nearly one-octave bandwidth from a hollow fiber
K. Yamane, A. Iwasaki, T. Tanigawa, T. Sekikawa, M. Yamashita
Optics InfoBase Conference Papers, 2007年01月01日
We developed an angularly dispersed noncollinear optical parametric amplifier with a 300-THz bandwidth (550 - 1000 nm) for the first time. To the best of our knowledge, this is the broadest parametric gain. © 2006 Optical Society of America.

Optical parametric amplification of optical pulses with a nearly one-octave bandwidth from a hollow fiber
K. Yamane, A. Iwasaki, T. Tanigawa, T. Sekikawa, M. Yamashita
Optics InfoBase Conference Papers, 2007年01月01日
We developed an angularly dispersed noncollinear optical parametric amplifier with a 300-THz bandwidth (550 - 1000 nm) for the first time. To the best of our knowledge, this is the broadest parametric gain. © 2006 Optical Society of America.

Efficient compression of carrier-envelope phase-locked laser pulses to 5 fs using an aluminum-coated hollow fiber
Eisuke Haraguchi, Takashi Tanigawa, Eiichi Matsubara, Keisaku Yamane, Mikio Yamashita, Taro Sekikawa
Optics InfoBase Conference Papers, 2007年01月01日
Carrier-envelope phase-lacked 0.13-TW, 5.2-fs laser pulses were generated by using a 56-cm-long aluminum-coated hollow fiber with an efficiency of 66 %, improved by coating aluminum inside the fiber with a core diameter of 500-μm. ©2007 Optical Society of America.

Optical parametric amplification of optical pulses with a nearly one-octave bandwidth from a hollow fiber
K. Yamane, A. Iwasaki, T. Tanigawa, T. Sekikawa, M. Yamashita
Optics InfoBase Conference Papers, 2007年01月01日
We developed an angularly dispersed noncollinear optical parametric amplifier with a 300-THz bandwidth (550 - 1000 nm) for the first time. To the best of our knowledge, this is the broadest parametric gain. © 2006 Optical Society of America.

Carrier-envelop-phase stabilized 3.3-fs optical pulses in the monocycle region
K. Yamane, T. Naoi, R. Morita, K. Sugiyama, M. Kitano, M. Yamashita
Optics InfoBase Conference Papers, 2006年01月01日
A system generating 3.3-fs optical pulses with a carrier-envelope-phase stabilized, quasi-monocycle waveform (500-nJ pulse energy, 470-to-1060 nm spectral width,1-kHz repetition rate) has been developed for the first time. © 2005 Optical Society of America.

Comparison between photonic crystal fiber and tapered fiber for pulse compression - toward mono-cycle optical pulses-
Muneyuki Adachi, Keisaku Yamane, Ryuji Morita, Mikio Yamashita
Optics InfoBase Conference Papers, 2006年01月01日
A feedback system that combined modified-SPIDER and 4-f active-chirp compensation enabled us to compress photonic-crystal-fiber and tapered-fiber outputs to 5.8 and 8.4 fs, respectively. Advantages and problems of both fibers for further pulse compression were mentioned. © 2005 Optical Society of America.

Few-cycle pulse compression using microstructured fibers
Muneyuki Adachi, Keisaku Yamane, Ryuji Marita, Mikio Yamashita
Conference on Lasers and Electro-Optics Europe - Technical Digest, 2005年12月01日

Generation of carrier-envelop-phase stabilized 3.3-fs optical pulses
K. Yamane, T. Naoi, A. Suguro, R. Morita, M. Yamashita, K. Sugiyama, M. Kitano
Conference on Lasers and Electro-Optics Europe - Technical Digest, 2005年12月01日

Nonlinear optical phenomena in gas-filled or microstructured fibers for few- to mono-cycle pulses
R. Morita, K. Yamane, M. Adachi, M. Yamashita
IQEC, International Quantum Electronics Conference Proceedings, 2005年12月01日
Nonlinear optical phenomena dominating spectral broadening and spectral phase behavior of pulses propagated in gas-filled or microstructure fibers for compression up to few- to mono-cycle region were discussed from the standpoint of time-frequency characteristics.

Comparison between photonic crystal fiber and tapered fiber for pulse compression - Toward mono-cycle optical pulses
Muneyuki Adachi, Keisaku Yamane, Ryuji Morita, Mikio Yamashita
Quantum Electronics and Laser Science Conference (QELS), 2005年10月31日
A feedback system that combined modified-SPIDER and 4-f active-chirp compensation enabled us to compress photonic-crystal-fiber and tapered-fiber outputs to 5.8 and 8.4 fs, respectively. Advantages and problems of both fibers for further pulse compression were mentioned. © 2005 Optical Society of America.

Carrier-envelop-phase stabilized 3.3-fs optical pulses in the monocycle region
K. Yamane, T. Naoi, R. Morita, K. Sugiyama, M. Kitano, M. Yamashita
Quantum Electronics and Laser Science Conference (QELS), 2005年10月31日
A system generating 3.3-fs optical pulses with a carrier-envelope-phase stabilized, quasi-monocycle waveform (500-nJ pulse energy, 470-to-1060 nm spectral width, 1-kHz repetition rate) has been developed for the first time. © 2004 Optical Society of America.

Comparison between photonic crystal fiber and tapered fiber for pulse compression - toward mono-cycle optical pulses-
Muneyuki Adachi, Keisaku Yamane, Ryuji Morita, Mikio Yamashita
Optics InfoBase Conference Papers, 2005年01月01日
A feedback system that combined modified-SPIDER and 4-f active-chirp compensation enabled us to compress photonic-crystal-fiber and tapered-fiber outputs to 5.8 and 8.4 fs, respectively. Advantages and problems of both fibers for further pulse compression were mentioned. © 2005 Optical Society of America.

Carrier-envelop-phase stabilized 3.3-fs optical pulses in the monocycle region
K. Yamane, T. Naoi, R. Morita, K. Sugiyama, M. Kitano, M. Yamashita
Optics InfoBase Conference Papers, 2005年01月01日
A system generating 3.3-fs optical pulses with a carrier-envelope-phase stabilized, quasi-monocycle waveform (500-nJ pulse energy, 470-to-1060 nm spectral width,1-kHz repetition rate) has been developed for the rst time. © 2004 Optical Society of America.

Comparison between photonic crystal fiber and tapered fiber for pulse compression - toward mono-cycle optical pulses
Muneyuki Adachi, Keisaku Yamane, Ryuji Morita, Mikio Yamashita
Optics InfoBase Conference Papers, 2005年01月01日
A feedback system that combined modified-SPIDER and 4-f active-chirp compensation enabled us to compress photonic-crystal-fiber and tapered-fiber outputs to 5.8 and 8.4 fs, respectively. Advantages and problems of both fibers for further pulse compression were mentioned. © 2005 Optical Society of America.

Carrier-envelop-phase stabilized 3.3-fs optical pulses in the monocycle region
K. Yamane, T. Naoi, R. Morita, K. Sugiyama, M. Kitano, M. Yamashita
Optics InfoBase Conference Papers, 2005年01月01日
A system generating 3.3-fs optical pulses with a carrier-envelope-phase stabilized, quasi-monocycle waveform (500-nJ pulse energy, 470-to-1060 nm spectral width,1-kHz repetition rate) has been developed for the first time. © 2005 Optical Society of America.

Microstructured fiber feedback pulse compression to few optical cycles
Muneyuki Adachi, Muneyuki Adachi, Keisaku Yamane, Ryuji Morita, Mikio Yamashita
Springer Series in Chemical Physics, 2004年12月01日
A feedback system that combined modified-SPIDER and 4-f active-chirp compensation enabled us to compress photonic-crystal-fiber and tapered-fiber outputs to 6.6 and 8.4 fs, respectively. Compressed-pulse results well agree with fringe-resolved autocorrelation measurement ones.

Time-frequency analysis of sub-4 fs optical pulses with over-one-octave bandwidth using Wigner distribution function
Ryuji Morita, Hayato Takenaka, Keisaku Yamane, Mikio Yamashita
Conference on Lasers and Electro-Optics Europe - Technical Digest, 2003年12月01日
In this paper, we analyze temporal and spectral properties of sub-4 fs optical pulses with over-one-octave bandwidth using Wigner distribution function (WDF). The analytic results suggested that WDF enables us to intuitively and usefully obtain more information about the deviation from the perfect Fourier transform limited FTL pulse than other representations for monocycle-like pulse generation. © 2003 IEEE.

Sub-4 fs optical-pulse generation using a feedback chirp-compensation method
Keisaku Yamane, Zhigang Zhang, Akira Suguro, Ryuji Morita, Mikio Yamashita
OSA Trends in Optics and Photonics Series, 2003年01月01日
We compensated for chirp of ultrabroad-band pulses with over-one-octave bandwidth using a feedback method. Consequently, we found the duration of compensated pulses is 4.0 fs. Furthermore, the generation of 3.6-fs pulses with sub-pulses was confirmed. © 2002 Optical Society of America.

Characterization of 3.4-fs optical pulses generated in the monocycle region
Keisaku Yamane, Zhigang Zhang, Akira Suguro, Ryuji Morita, Mikio Yamashita
OSA Trends in Optics and Photonics Series, 2003年01月01日
We have characterized ultrabroad-band optical pulses with over-one-octave bandwidth (495 - 1090 nm) by use of an improved modifled-SPIDER apparatus and compressed the pulses to 3.4-fs (1.56 cycles) by a feedback phase compensation. © 2003 Optical Society of America.

A study on novel spectral behaviors of ultrabroad-band optical pulses generated by induced-phase modulation in a gas-filled hollow fiber using a modified SPIDER technique
Keisaku Yamane, Naoki Karasawa, Satoru Kusaka, Masakatsu Hirasawa, Akira Suguro, Hidemi Shigekawa, Ryuji Morita, Mikio Yamashita
Pacific Rim Conference on Lasers and Electro-Optics, CLEO - Technical Digest, 2002年01月01日
Spectral behaviors of ultrabroad-band optical pulses generated by induced-phase modulation in a gas-filled hollow fiber using a modified SPIDER technique were discussed. Pulse-shaper output spectra of the ultrabroad-band optical pulses from 350 to 700 nm was shown. Results showed that the interferometric structure was lost in the spectral region from 310 to 333 nm in ∼1s but was clear in the 333 to 370 nm region.

光ファイバにおける量子Zeno効果
山根 啓作, 伊藤 雅弘, 北野 正雄
電子情報通信学会技術研究報告. LQE, レーザ・量子エレクトロニクス, 2000年01月19日, 日本語
量子Zeno効果は散逸過程が関与しているにもかかわらず損失無しに状態遷移の抑制あるいは系の誘導を行うことが出来る点において逆接的な現象である.Zeno効果は量子系に限定されない普遍的な現象である.本論文では古典系における例として軸をずらせて接続されたファイバー列における量子Zeno効果について報告する.ここではファイバ列に対して光を入射した場合の光の透過率を調べることで量子Zeno効果の検証を行なう.ファイバにおける光の伝搬様式には波動的な場合と光線的な場合が存在するが, 量子Zeno効果は波動的な伝搬をする場合にのみ存在することが分かった.その場合, 接続部における不連続性にも関わらず光の透過率は接続段の増加とともに1に収束することが分かった.

光ファイバにおける量子Zeno効果
山根 啓作, 伊藤 雅弘, 北野 正雄
電子情報通信学会技術研究報告. PS, 光スイッチング, 2000年01月19日, 日本語
量子Zeno効果は散逸過程が関与しているにもかかわらず損失無しに状態遷移の抑制あるいは系の誘導を行うことが出来る点において逆接的な現象である.Zeno効果は量子系に限定されない普遍的な現象である.本論文では古典系における例として軸ををずらせて接続されたファイバー列における量子Zeno効果について報告する.ここではファイバ列に対して光を入射した場合の光の透過率を調べることで量子Zeno効果の検証を行なう.ファイバにおける光の伝搬様式には波動的な場合と光線的な場合が存在するが, 量子Zeno効果は波動的な伝搬をする場合にのみ存在することが分かった.その場合, 接続部における不連続性にも関わらず光の透過率は接続段の増加とともに1に収束することが分かった.

光ファイバにおける量子Zeno効果
山根 啓作, 伊藤 雅弘, 北野 正雄
電子情報通信学会技術研究報告. OPE, 光エレクトロニクス, 2000年01月19日, 日本語
量子Zeno効果は散逸過程が関与しているにもかかわらず損失無しに状態遷移の抑制あるいは系の誘導を行うことが出来る点において逆接的な現象である.Zeno効果は量子系に限定されない普遍的な現象である.本論文では古典系における例として軸をずらせて接続されたファイバー列における量子Zeno効果について報告する.ここではファイバ列に対して光を入射した場合の光の透過率を調べることで量子Zeno効果の検証を行なう.ファイバにおける光の伝搬様式には波動的な場合と光線的な場合が存在するが, 量子Zeno効果は波動的な伝搬をする場合のみ存在することが分かった.その場合, 接続部における不連続性にも関わらず光の透過率は接続段の増加とともに1に収束することが分かった.

光ファイバにおける量子 Zeno 効果
山根 啓作, 伊藤 雅弘, 北野 正雄
電気学会研究会資料. : The Papers of Technical Meeting on Electromagnetic Theory, IEE Japan. EMT, 電磁界理論研究会, 2000年01月19日, 日本語

量子Zeno効果による原子スピン制御
山根 啓作, 生島 剛, 北野 正雄, 小倉 久直
レーザー学会学術講演会年次大会講演予稿集 = Annual meeting, of the Laser Society of Japan digest of technical papers, 1997年01月01日, 日本語

量子Zeno効果による原子スピン制御
山根 啓作, 生島 剛, 北野 正雄, 小倉 久直
日本物理学会講演概要集. 秋の分科会, 1996年09月13日, 日本語

29a-YP-1 半導体レーザによるRb原子のレーザ冷却III
山根 啓作, 吉田 明生, 十倉 俊之, 北野 正雄, 小倉 久直
日本物理学会講演概要集. 年会, 1995年03月16日, 日本語

29a-E-5 半導体レーザによるRb原子のレーザ冷却 II
吉田 明生, 山根 啓作, 十倉 俊之, 北野 正雄, 小倉 久直
日本物理学会講演概要集. 年会, 1994年03月16日, 日本語

13a-DA-8 半導体レーザによるRb原子のレーザ冷却
吉田 明生, 上野 洋史, 山根 啓作, 北野 正雄, 小倉 久直
日本物理学会講演概要集. 秋の分科会, 1993年09月20日, 日本語

光圧を極める：分子操作の極限化と光制御によるマクロ化
科学研究費助成事業
2016年06月30日 - 2021年03月31日
笹木 敬司, 村越 敬, 森田 隆二, 深港 豪, 山根 啓作
分子や分子集団に働く光圧の強さや方向をナノメートル空間の各点毎に自在に制御することにより、如何に小さい物質を如何に高い精度で光マニピュレーションできるかという極限性能の追究を目指している。具体的な研究課題としては、１）単一分子レベル光操作：ナノサイズの光局在場により室温・媒質中において分子を個別選択的に捕捉・操作し、配置・配向・配列を制御する技術の開発、２）ナノ空間の光圧デザイン：光電場の振幅・位相・偏光をシングルナノメートルスケールで成形する手法を開発し、分子・分子集合体の形状選別トラッピングやナノ光渦による分子の回転運動（分子渦）・キラル構造形成等の実現、３）光操作システムのマクロ化：基板の大面積化・集積化や多様な光圧制御技術による光ナノ物質操作のマクロ化に挑戦している。今年度は、１）ナノファイバーによるナノ粒子選別輸送と光圧スペクトロスコピーに関する実験実証と、ナノダイヤモンドに作用する共鳴吸収力・散乱力や光圧測定精度の定量的な解析を実施した。また、２）デザインした金属ナノ構造体によるナノ空間角運動量制御により、ダイヤモンドナノ粒子をナノ空間で回転運動を誘起する実験に成功するとともに、超解像イメージング技術を応用展開して、ナノメートルの精度でナノ粒子の運動を可視化する技術を開発した。さらに３）分子ナノ粒子のプラズモニックギャップ捕捉・配置・配列およびキラル分子集合体ナノ粒子の高感度円二色性分光法を開発した。
日本学術振興会, 新学術領域研究(研究領域提案型), 北海道大学, 16H06506

光波のハイパースペクトラル制御を用いた超短光パルス時空間制御装置の開発
科学研究費助成事業
2017年04月01日 - 2020年03月31日
山根 啓作
サニャック干渉計型光学配置及び空間光変調器を用いた独自の光波変換装置を開発し、高効率かつ高い自由度で光波の時空間制御が可能な装置を開発した。本装置により、超短パルス光のビーム断面の強度分布を 1.方位方向、2.動径方向、3. 1次元方向など、様々なパターンにおいて、ピコ秒域という超短時間域で自在に超高速制御することに成功した。また、本技術の高い柔軟性を応用することで光の偏光状態をピコ秒域で制御することにも成功した。
日本学術振興会, 基盤研究(C), 北海道大学, 17K05069

波長キャリアと空間キャリアの融合によるチャネルド偏光計測法の新展開
科学研究費助成事業
2015年04月01日 - 2018年03月31日
岡 和彦, 山根 啓作
チャネルド偏光計測法は、偏光状態の波長ないし空間分布を、波長キャリアないし空間キャリアを利用して測定する方法である。本研究の目的は、この波長ないし空間キャリアを柔軟に活用する新たな偏光計測・制御法を開発することであった。第１の成果は、この原理に基づくハイパー分光ミューラー行列偏光計の開発である。第２に、高次移相子とチャープパルスを用いた偏光およびリング状光格子の超高速回転法も開発した。
日本学術振興会, 基盤研究(B), 15H04011