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Keisaku Yamane
Faculty of Engineering　Applied Physics　Optical Science and Technology
Associate Professor
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Last Updated :2024/05/09

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Affiliation

  • Faculty of Engineering　Applied Physics　Optical Science and Technology

Job Title

  • Associate Professor

J-Global ID

Research Areas

  • Natural sciences / Semiconductors, optical and atomic physics

Educational Organization

Research Activities

Published Papers

  • 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) 2024/03/01 
    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.
  • Yasunori Toda, Satoshi Tsuchiya, Keisaku Yamane, Ryuji Morita, Migaku Oda, Tohru Kurosawa, Tomaz Mertelj, Dragan Mihailovic
    Optics Express 31 (11) 17537 - 17537 2023/05/10 
    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.
  • 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) 2022/12/08
  • Asami Honda, Keisaku Yamane, Kohei Iwasa, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
    Scientific reports 12 (1) 18674 - 18674 2022/11/04
  • Asami Honda, Keisaku Yamane, Kohei Iwasa, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
    Scientific reports 12 (1) 14991 - 14991 2022/09/02 
    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.
  • Takashige Omatsu, Katsuhiko Miyamoto, Ken-Ichi Yuyama, Keisaku Yamane, Ryuji Morita
    Journal of Photochemistry and Photobiology C: Photochemistry Reviews 52 100535 - 100535 1389-5567 2022/09
  • Yuji Sasaki, Kenji Yamazaki, Naoshi Murakami, Keisaku Yamane, Hiroshi Orihara
    Advanced Photonics Research 3 (8) 2100368 - 2100368 2699-9293 2022/08 [Refereed][Not invited]
  • 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 2192-8606 2022/02 
    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'.
  • 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 
    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.
  • 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 
    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.
  • Masato Suzuki, Keisaku Yamane, Takashige Omatsu, Ryuji Morita
    NEW JOURNAL OF PHYSICS 23 (11) 1367-2630 2021/11 
    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.
  • Haruki Kawaguchi, Kei Umesato, Kanta Takahashi, Keisaku Yamane, Ken-ichi Yuyama, Satoyuki Kawano, Katsuhiko Miyamoto, Takadhige Omatsu
    Optical Manipulation and Structured Materials Conference 2021 2021/10/27
  • Kazuhiko Oka, Keisaku Yamane, Moritsugu Sakamoto, Ryuji Morita
    Proceedings of SPIE - The International Society for Optical Engineering 11927 0277-786X 2021 
    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.
  • Kohki Nakagawa, Keisaku Yamane, Ryuji Morita, Yasunori Toda
    APPLIED PHYSICS EXPRESS 13 (4) 042001/1 - 5 1882-0778 2020/04 [Refereed][Not invited]
     
    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.
  • Ami Shiraishi, Keigo Masuda, Keisaku Yamane, Kohei Toyoda, Katsuhiko Miyamoto, Takashige Omatsu
    2020 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO) 2160-9020 2020 
    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)
  • Rin Sasaki, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda, Takashige Omatsu, Ryuji Morita
    Proceedings of SPIE - The International Society for Optical Engineering 11522 0277-786X 2020 
    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.
  • Haruki Kawaguchi, Kei Umesato, Keisaku Yamane, Katsuhiko Miyamoto, Takashige Omatsu
    Proceedings of SPIE - The International Society for Optical Engineering 11522 0277-786X 2020 
    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.
  • Ami Shiraishi, Keigo Masuda, Keisaku Yamane, Kohei Toyoda, Katsuhiko Miyamoto, Takashige Omatsu
    Optics InfoBase Conference Papers Part F183-CLEO-SI 2020 1092-8081 2020 
    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.
  • Keigo Masuda, Ryo Shinozaki, Ami Shiraishi, Mitsuki Ichijo, Keisaku Yamane, Katsuhiko Miyamoto, Takashige Omatsu
    Journal of Nanophotonics 14 (1) 1934-2608 2020/01/01 
    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.
  • Masato Suzuki, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
    Scientific Reports 9 (1) 2045-2322 2019/12/01 [Refereed][Not invited]
     
    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.
  • Keigo Masuda, Mitsuki Ichijo, Ryo Shinozaki, Keisaku Yamane, Katsuhiko Miyamoto, Takashige Omatsu
    Proceedings of SPIE - The International Society for Optical Engineering 11141 0277-786X 2019 
    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.
  • Keisaku Yamane, Kohei Iwasa, Rin Sasaki, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
    Proceedings of SPIE - The International Society for Optical Engineering 11141 0277-786X 2019 
    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.
  • Keigo Masuda, Mitsuki Ichijo, Ryo Sinozaki, Keisaku Yamane, Katsuhiko Miyamoto, Takashige Omatsu
    Optics InfoBase Conference Papers Part F146-JSAP 2019 2019
  • Y. Toda, K. Nakagawa, K. Yamane, R. Morita, Y. Awaji
    Proceedings of SPIE - The International Society for Optical Engineering 11141 0277-786X 2019 
    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.
  • Keisaku Yamane, Kohei Iwasa, Rin Sasaki, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
    Optics InfoBase Conference Papers Part F140-CLEO_Europe 2019 2019 
    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].
  • Keisaku Yamane, Yuho Watanabe, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
    Optics InfoBase Conference Papers Part F140-CLEO_Europe 2019 2019 
    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.
  • 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 [Refereed][Not invited]
     
    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.
  • 山根啓作
    電子情報通信学会論文誌 C(Web) J101-C (12) 509‐517 (WEB ONLY)  1881-0217 2018/12/01 [Not refereed][Not invited]
  • Masato Suzuki, Keisaku Yamane, Moritsugu Sakamoto, O. K.A. Kazuhiko, Yasunori Toda, Ryuji Morita
    Optics Express 26 (3) 2584 - 2598 1094-4087 2018/02/05 [Refereed][Not invited]
     
    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.
  • Keisaku Yamane, Yuho Watanabe, Isamu Wakisaka, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
    Optics InfoBase Conference Papers Part F114-FIO 2018 2018 
    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.
  • Ryuji Morita, Masato Suzuki, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda
    Proceedings of SPIE - The International Society for Optical Engineering 10549 0277-786X 2018 [Refereed][Not invited]
     
    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.
  • 山根啓作, 森田隆二
    光アライアンス 日本工業出版 28 (9) 31‐35 - 30 0917-026X 2017/09 [Not refereed][Not invited]
  • 山根 啓作, 森田 隆二
    光アライアンス 日本工業出版 28 (9) 31 - 35 0917-026X 2017/09 [Not refereed][Not invited]
  • Y. Toda, A. Moriya, K. Yamane, R. Morita, K. Shigematsu, Y. Awaji
    APPLIED PHYSICS LETTERS 111 (10) 0003-6951 2017/09 [Not refereed][Not invited]
     
    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).
  • 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) 2017 [Refereed][Not invited]
  • Y. Toda, H. Moriya, K. Shigematsu, K. Yamane, R. Morita, Y. Awaji
    OPTICAL MANIPULATION CONFERENCE 10252 0277-786X 2017 [Refereed][Not invited]
     
    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.
  • Keisaku Yamane, Kohei Iwasa, Kohei Kakizawa, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
    OPTICAL MANIPULATION CONFERENCE 10252 0277-786X 2017 [Refereed][Not invited]
     
    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.
  • Kyohhei Shigematsu, Masato Suzuki, Keisaku Yamane, Ryuji Morita, Yasunori Toda
    APPLIED PHYSICS EXPRESS 9 (12) 1882-0778 2016/12 [Not refereed][Not invited]
     
    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
  • Masato Suzuki, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
    Physical Review A - Atomic, Molecular, and Optical Physics 94 1050-2947 2016/10/26 [Not refereed][Not invited]
     
    © 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.
  • Masato Suzuki, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
    PHYSICAL REVIEW A 94 (4) 2469-9926 2016/10 [Refereed][Not invited]
     
    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.
  • K. Yamane, M. Sakamoto, N. Murakami, R. Morita, K. Oka
    OPTICS LETTERS 41 (19) 4597 - 4600 0146-9592 2016/10 [Not refereed][Not invited]
     
    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
  • Fuyuto Takahashi, Katsuhiko Miyamoto, Hirofumi Hidai, Keisaku Yamane, Ryuji Morita, Takashige Omatsu
    SCIENTIFIC REPORTS 6 21738  2045-2322 2016/02 [Refereed][Not invited]
     
    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.
  • K. Shigematsu, K. Yamane, R. Morita, Y. Toda
    Physical Review B - Condensed Matter and Materials Physics 93 1098-0121 2016/01/15 [Not refereed][Not invited]
     
    © 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.
  • Uchikoga R., Shigematsu K., Yamane K., Morita R., Toda Y.
    Meeting Abstracts of the Physical Society of Japan 一般社団法人 日本物理学会 71 (2) 1414 - 1414 2189-079X 2016 

    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。

  • K. Shigematsu, K. Yamane, R. Morita, Y. Toda
    PHYSICAL REVIEW B 93 (4) 2469-9950 2016/01 [Refereed][Not invited]
     
    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.
  • Masato Suzuki, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
    SCIENTIFIC REPORTS 5 17797  2045-2322 2015/12 [Refereed][Not invited]
     
    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.
  • 岡 和彦, 坂本 盛嗣, 山根 啓作
    O plus E : Optics・Electronics アドコム・メディア 37 (4) 263 - 268 0911-5943 2015/04 [Not refereed][Not invited]
  • Masato Suzuki, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
    OPTICAL REVIEW 22 (1) 179 - 183 1340-6000 2015/02 [Not refereed][Not invited]
     
    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.
  • Masato Suzuki, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
    2015 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO) 2160-9020 2015 [Refereed][Not invited]
     
    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
  • Masato Suzuki, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
    OPTICS EXPRESS 22 (14) 16903 - 16915 1094-4087 2014/07 [Refereed][Not invited]
     
    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
  • Masato Suzuki, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
    OPTICS EXPRESS 22 (14) 16903 - 16915 1094-4087 2014/07 [Not refereed][Not invited]
     
    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
  • Keisaku Yamane, Zhili Yang, Yasunori Toda, Ryuji Morita
    NEW JOURNAL OF PHYSICS 16 (May) 053020 (WEB ONLY)  1367-2630 2014/05 [Not refereed][Not invited]
     
    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.
  • Kyohhei Shigematsu, Keisaku Yamane, Ryuji Morita, Yasunori Toda
    2014 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO) 2160-9020 2014 [Refereed][Not invited]
     
    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.
  • Keisaku Yamane, Yasuyuki Shioda, Masato Suzuki, Yasunori Toda, Ryuji Morita
    2014 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO) 2160-9020 2014 [Refereed][Not invited]
     
    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
  • Ryuji Morita, Keisaku Yamane, Zhili Yang, Yasunori Toda
    COMPLEX LIGHT AND OPTICAL FORCES VIII 8999 0277-786X 2014 [Not refereed][Not invited]
     
    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.
  • Kyohhei Shigematsu, Yasunori Toda, Keisaku Yamane, Ryuji Morita
    JAPANESE JOURNAL OF APPLIED PHYSICS 52 (8) 0021-4922 2013/08 [Not refereed][Not invited]
     
    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
  • Masato Suzuki, Keisaku Yamane, Yasunori Toda, Ryuji Morita
    2013 CONFERENCE ON LASERS AND ELECTRO-OPTICS PACIFIC RIM (CLEO-PR) 2013 [Refereed][Not invited]
     
    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.
  • Masato Suzuki, Keisaku Yamane, Yasunori Toda, Ryuji Morita
    2013 CONFERENCE ON LASERS AND ELECTRO-OPTICS EUROPE AND INTERNATIONAL QUANTUM ELECTRONICS CONFERENCE (CLEO EUROPE/IQEC) 2013 [Refereed][Not invited]
  • Keisaku Yamane, Asami Honda, Kyohhei Shigematsu, Yasunori Toda, Ryuji Morita
    2013 CONFERENCE ON LASERS AND ELECTRO-OPTICS PACIFIC RIM (CLEO-PR) 2013 [Refereed][Not invited]
     
    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.
  • Zhili Yang, Keisaku Yamane, Yasunori Toda, Ryuji Morita
    2013 CONFERENCE ON LASERS AND ELECTRO-OPTICS PACIFIC RIM (CLEO-PR) 2013 [Refereed][Not invited]
     
    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.
  • Zhili Yang, Keisaku Yamane, Yasunori Toda, Ryuji Morita
    2013 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO) 2160-9020 2013 [Refereed][Not invited]
     
    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.
  • Keisaku Yamane, Yasunori Toda, Ryuji Morita
    2013 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO) 2160-9020 2013 [Refereed][Not invited]
     
    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
  • Y. Toda, K. Shigematsu, K. Yamane, R. Morita
    Optics Communications 308 147 - 151 0030-4018 2013 [Not refereed][Not invited]
     
    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.
  • Keisaku Yamane, Yasunori Toda, Ryuji Morita
    OPTICS EXPRESS 20 (17) 18986 - 18993 1094-4087 2012/08 [Refereed][Not invited]
     
    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
  • 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 1010-6030 2011/09 [Not refereed][Not invited]
     
    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.
  • Keisaku Yamane, Masato Katayose, Mikio Yamashita
    IEEE PHOTONICS TECHNOLOGY LETTERS 23 (16) 1130 - 1132 1041-1135 2011/08 [Not refereed][Not invited]
     
    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.
  • Takashi Tanigawa, Keisaku Yamane, Naoki Karasawa, Mikio Yamashita
    JAPANESE JOURNAL OF APPLIED PHYSICS 50 (7) 0021-4922 2011/07 [Not refereed][Not invited]
     
    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
  • Jiangfeng Zhu, Shaobo Fang, Keisaku Yamane, Mikio Yamashita
    IEEE JOURNAL OF QUANTUM ELECTRONICS 47 (6) 810 - 818 0018-9197 2011/06 [Not refereed][Not invited]
     
    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.
  • Shaobo Fang, Keisaku Yamane, Jiangfeng Zhu, Chun Zhou, Zhigang Zhang, Mikio Yamashita
    IEEE PHOTONICS TECHNOLOGY LETTERS IEEE 23 (11) 688 - 690 1041-1135 2011/06 [Not refereed][Not invited]
     
    We succeeded in generating 860-mu J 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 copropagation 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 ultra-broadband spectroscopy and quantum control as well as attosecond science and technology.
  • Shaobo Fang, Keisaku Yamane, Jiangfeng Zhu, Chun Zhou, Zhigang Zhang, Mikio Yamashita
    2011 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO) 2160-9020 2011 [Refereed][Not invited]
     
    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.
  • Zhu J, Tanigawa T, Chen T, Fang S, Yamane K, Sekikawa T, Yamashita M
    Applied optics 3 49 (3) 350 - 357 0003-6935 2010/01 [Refereed][Not invited]
  • Jiangfeng Zhu, Takashi Tanigawa, Tao Chen, Shaobo Fang, Keisaku Yamane, Taro Sekikawa, Mikio Yamashita
    APPLIED OPTICS 49 (3) 350 - 357 1559-128X 2010/01 [Refereed][Not invited]
     
    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
  • 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) 2010 [Refereed][Not invited]
     
    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
  • 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 - + 2009 [Refereed][Not invited]
     
    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
  • Takashi Tanigawa, Keisaku Yamane, Taro Sekikawa, Mikio Yamashita
    ULTRAFAST PHENOMENA XVI 92 759 - + 0172-6218 2009 [Refereed][Not invited]
     
    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.
  • K. Yamane, T. Tanigawa, T. Sekikawa, M. Yamashita
    OPTICS EXPRESS 16 (22) 18345 - 18353 1094-4087 2008/10 [Not refereed][Not invited]
     
    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
  • 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 - + 2008 [Refereed][Not invited]
     
    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
  • YAMASHITA Mikio, YAMANE Keisaku, MORITA Ryuji
    應用物理 応用物理学会 76 (2) 154 - 159 0369-8009 2007/02/10 [Not refereed][Not invited]
  • YAMANE Keisaku, YAMASHITA Mikio
    Japanese journal of optics 応用物理学会分科会日本光学会 36 (2) 88 - 90 0389-6625 2007/02/10 [Not refereed][Not invited]
  • Eiichi Matsubara, Keisaku Yamane, Toshiyuki Naoi, Toshihiko Kito, Eisuke Haraguchi, Taro Sekikawa, Mikio Yamashita
    ULTRAFAST PHENOMENA XV 88 113 - + 0172-6218 2007 [Refereed][Not invited]
     
    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.
  • 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 - + 2007 [Refereed][Not invited]
     
    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
  • 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 2007 [Refereed][Not invited]
     
    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
  • Eiichi Matsubara, Keisaku Yamane, Taro Sekikawa, Mikio Yamashita
    Journal of the Optical Society of America B: Optical Physics 24 (4) 985 - 989 0740-3224 2007 [Not refereed][Not invited]
     
    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.
  • Mikio Yamashita, Keisaku Yamane, Ryuji Morita
    IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS 12 (2) 213 - 222 1077-260X 2006/03 [Not refereed][Not invited]
     
    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.
  • Muneyuki Adachi, Keisaku Yamane, Ryuji Marita, Mikio Yamashita
    Conference on Lasers and Electro-Optics Europe - Technical Digest 2005 [Refereed][Not invited]
  • R. Morita, K. Yamane, M. Adachi, M. Yamashita
    IQEC, International Quantum Electronics Conference Proceedings 2005 544 - 545 2005 [Refereed][Not invited]
     
    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.
  • M Adachi, K Yamane, R Morita, M Yamashita
    ULTRAFAST PHENOMENA XIV 79 49 - 51 0172-6218 2005 [Refereed][Not invited]
     
    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.
  • M Adachi, K Yamane, R Morita, M Yamashita
    JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS 44 (46-49) L1423 - L1425 0021-4922 2005 [Not refereed][Not invited]
     
    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.
  • Yuqiang Deng, Zubin Wu, Lu Chai, Ching-Yue Wang, Keisaku Yamane, Ryoji Morita, Mikio Yamashita, Zhigang Zhang
    Optics Express 13 (6) 2120 - 2126 1094-4087 2005 [Not refereed][Not invited]
     
    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.
  • K Yamane, T Kito, R Morita, M Yamashita
    ULTRAFAST PHENOMENA XIV 79 13 - 15 0172-6218 2005 [Not refereed][Not invited]
     
    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.
  • M Adachi, K Yamane, R Morita, M Yamashita
    IEEE PHOTONICS TECHNOLOGY LETTERS 16 (8) 1951 - 1953 1041-1135 2004/08 [Not refereed][Not invited]
     
    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.
  • K Yamane, ZG Zhang, A Suguro, K Oka, R Morita, M Yamashita
    ULTRAFAST OPTICS IV 95 97 - 102 0342-4111 2004 [Refereed][Not invited]
     
    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.
  • Ryuji Morita, Keisaku Yamane, Mikio Yamashita
    OSA Trends in Optics and Photonics Series 96 A 793 - 795 1094-5695 2004/01/01 [Not refereed][Not invited]
     
    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.
  • Muneyuki Adachi, Keisaku Yamane, Ryuji Morita, Mikio Yamashita
    OSA Trends in Optics and Photonics Series 96 A 783 - 785 1094-5695 2004/01/01 [Not refereed][Not invited]
     
    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.
  • K. Yamane, T. Kito, R. Morita, M. Yamashita
    Optics Express 12 (12) 2762 - 2773 1094-4087 2004 [Not refereed][Not invited]
     
    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.
  • K Yamane, ZG Zhang, K Oka, R Morita, M Yamashita, A Suguro
    OPTICS LETTERS 28 (22) 2258 - 2260 0146-9592 2003/11 [Refereed][Not invited]
     
    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.
  • Ryuji Morita, Hayato Takenaka, Keisaku Yamane, Mikio Yamashita
    Conference on Lasers and Electro-Optics Europe - Technical Digest 455  2003 [Refereed][Not invited]
     
    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.
  • 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 0957-0233 2002/11 [Not refereed][Not invited]
     
    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.
  • T Nakanishi, K Yamane, M Kitano
    PHYSICAL REVIEW A 65 (1) 2469-9926 2002/01 [Not refereed][Not invited]
     
    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.
  • T. Nakanishi, K. Yamane, M. Kitano
    Physical Review A - Atomic, Molecular, and Optical Physics 65 (1) 4  1094-1622 2002 [Refereed][Not invited]
     
    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.
  • K Yamane, M Ito, M Kitano
    OPTICS COMMUNICATIONS 192 (3-6) 299 - 307 0030-4018 2001/06 [Refereed][Not invited]
     
    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.
  • KITANO Masao, YAMANE Keisaku
    The Review of laser engineering レ-ザ-学会 28 (10) 650 - 655 0387-0200 2000/10/15 [Not refereed][Not invited]
  • Nakanishi T, Yamane K, Kitano M
    Meeting abstracts of the Physical Society of Japan The Physical Society of Japan (JPS) 55 (2) 106 - 106 1342-8349 2000/09/10 [Not refereed][Not invited]
  • YAMANE Keisaku, ITO Masahiro, KITANO Masao
    Technical report of IEICE. OPE 一般社団法人電子情報通信学会 99 (544) 19 - 24 0913-5685 2000/01/19 [Not refereed][Not invited]
     
    The quantum Zeno effect is a seemingly paradoxical phenomenon where a inhibition of transition or a guidance of system is realized without losses in spite of the use of the dissipative processes. It is universal and not restricted to the quantum systems. In this paper as a classical example we report the quautum Zeno effect in a series of off-set spliced optical fibers. We verify the quantum Zeno effect by estimating the transmission coefficient of the fibers. There are two kinds of light propagation modes - wave and ray, and the quantum Zeno effect is found to be peculiar to the former mode. Despite of the discontinuity the transmission coefficient approaches unity as the increase of the number of joints.
  • YAMANE Keisaku, ITO Masahiro, KITANO Masao
    Technical report of IEICE. LQE 一般社団法人電子情報通信学会 99 (546) 19 - 24 0913-5685 2000/01/19 [Not refereed][Not invited]
     
    The quantum Zeno effect is a seemingly paradoxical phenomenon where a inhibition of transition or a guidance of system is realized without losses in spite of the use of the dissipative processes. It is universal and not restricted to the quantum systems. In this paper as a classical example we report the quautum Zeno effect in a series of off-set spliced optical fibers. We verify the quantum Zeno effect by estimating the transmission coefficient of the fibers. There are two kinds of light propagation modes - wave and ray, and the quantum Zeno effect is found to be peculiar to the former mode. Despite of the discontinuity the transmission coefficient approaches unity as the increase of the number of joints.
  • KITANO Masao, YAMANE Keisaku
    rle The Laser Society of Japan 28 (10) 650 - 655 0387-0200 2000 [Not refereed][Not invited]
     
    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.
  • M Kitano, K Yamane, T Ikushima
    PHYSICAL REVIEW A 59 (5) 3710 - 3713 1050-2947 1999/05 [Refereed][Not invited]
     
    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].

Conference Activities & Talks

MISC

Research Grants & Projects

  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2016/06 -2021/03 
    Author : 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。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2017/04 -2020/03 
    Author : Yamane Keisaku
     
    We developed a novel high efficiency converter for spatio-temporal control of ultrashort optical pulses based on a Sagnac-interferometer-type configuration. Thanks to flexibility of a spatial light modulator, ultrafast controls of the beam profiles were demonstrated in picosecond regime in various directions such as azimuth, radial, linear directions. Furthermore, ultrafast controls of polarization states were also employed by applying our unique technique for spatio-temporal control of ultrashort optical pulses.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2015/04 -2018/03 
    Author : OKA KAZUHIKO
     
    Channeled polarimetry is the method for measuring spectrally- or spatially-resolved polarization-distribution utilizing spectral or spatial carriers. This project aimed to develop new types of channeled polarization measurement and control techniques based on novel and flexible use of spectral and/or spatial carriers. We developed hyperspectroscopic Mueller-matrix polarimeters using both spatial and spectral carriers. In addition, ultrafast rotations of polarization and ring-shaped optical lattice were realized by use of a high-order retarder and a chirped pulse.

Educational Activities

Teaching Experience

  • Nonlinear Optics
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 工学院
    キーワード : 非線形分極，非線形感受率応答関数，非線形波動方程式，輻射と物質との相互作用，応答と分散，光パルスの非線形伝播，群速度，負の屈折率
  • Nonlinear Optics
    開講年度 : 2021
    課程区分 : 博士後期課程
    開講学部 : 工学院
    キーワード : 非線形分極，非線形感受率応答関数，非線形波動方程式，輻射と物質との相互作用，応答と分散，光パルスの非線形伝播，群速度，負の屈折率
  • Applied Physics Experiment I
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 物理学実験、実験方法、測定法、データ処理、物理現象
  • Applied Physics Experiment II
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 物理学実験、実験方法、測定法、データ処理、物理現象
  • Freshman Seminar
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : 波動、音波、超音波、超短パルスレーザー、光渦、シミュレーション、アルゴリズム
  • Practical Methods in Applied Physics
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 物理学実験，実験方法，測定法，機器取扱，データ処理
  • The World of Science and Technology
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : 光ピンセット、レーザー冷却、超短光パルス、レーザー医療、レーザー加工、光周波数コム、光渦
  • Freshman Seminar
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : 超伝導、ゼロ抵抗、マイスナー効果、人工雪、結晶成長、量子通信、天文観測技術，光学実験、フェムト秒レーザー、レーザー加工 材料科学、X線回折、結晶構造、熱膨張係数、構造材料、力学特性、微細組織

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