2015, 応用物理学会, 第37回優秀論文賞　　　　　　　　　　　　　　　
戸田泰則

Photoinduced Metal–Insulator Phase Separation Depending on the Conformational Order of Molecules in β-(BEDT-TTF)₂I₃
Kensho Nagata, Satoshi Tsuchiya, Koichi Nakagawa, Hiromi Taniguchi, Yasunori Toda
Journal of the Physical Society of Japan, 94, 4, Physical Society of Japan, 15 Apr. 2025
Scientific journal

Photoinduced quasiparticle dynamics of single CuO2 -layer Bi-based cuprates with out-of-plane disorder
T. Akiba, Y. Toda, S. Tsuchiya, M. Oda, T. Kurosawa, D. Mihailovic, T. Mertelj
Physical Review B, 109, 1, American Physical Society (APS), 09 Jan. 2024, [Peer-reviewed], [Corresponding author]
Scientific journal

Ultrafast Pump–Probe Spectroscopy in Organic Dirac Electron Candidate α-(BETS)2I3
Satoshi Tsuchiya, Masato Katsumi, Ryuhei Oka, Toshio Naito, Yasunori Toda
Condensed Matter, 8, 4, 88, 88, MDPI AG, 10 Oct. 2023
Scientific journal, Photo-induced carrier dynamics were measured in the organic Dirac electron candidate α-(BETS)2I3 to investigate why resistivity increases below TMI = 50 K. We found a change in carrier dynamics due to an insulating gap formation below T′ = 50 K. On the other hand, the relaxation time and polarization anisotropy of the observed dynamics differ from those in the charge-ordering (CO) state of the isostructural salt α-(ET)2I3. Based on the difference, it can be concluded that the insulating phase has a different origin than the CO state.

Effects of Molecular Substitution in Organic Conductors α-(ET)₂I₃ and α-(STF)₂I₃ Studied by Polarized Femtosecond Spectroscopy
Satoshi Tsuchiya, Naoki Kanai, Ryuhei Oka, Toshio Naito, Yasunori Toda
Journal of the Physical Society of Japan, 92, 9, 094703/1, 7, Physical Society of Japan, 15 Sep. 2023, [Peer-reviewed]
Scientific journal

Ultrafast Optical Spectroscopy in the Normal State of Organic Superconductor \(\beta \)-(BEDT-TTF)₂I₃
Satoshi Tsuchiya, Kensho Nagata, Hiromi Taniguchi, Yasunori Toda
Proceedings of the 29th International Conference on Low Temperature Physics (LT29), Journal of the Physical Society of Japan, 22 May 2023
International conference proceedings

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, 10 May 2023, [Peer-reviewed], [Lead author, Corresponding author]
Scientific journal, 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.

Probing uniform and nonuniform charge ordering with polarized femtosecond optical pulses in geometrically frustrated θ−(BEDT−TTF)2MZn(SCN)4(M = Rb,Cs )
K. Nakagawa, S. Tsuchiya, H. Taniguchi, Y. Toda
Physical Review Research, 5, 1, American Physical Society (APS), 19 Jan. 2023, [Peer-reviewed]
Scientific journal

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, 04 Nov. 2022, [International Magazine]
English

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, 02 Sep. 2022, [International Magazine]
English, Scientific journal, 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.

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
International conference proceedings

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
International conference proceedings

Coherent quench of superconducting state using optical vortex pulses
Y. Toda, S. Tsuchiya, K. Yamane, R. Morita, M. Oda, T. Mertelj, D. Mihailovic
Proceedings of the 2022 Conference on Lasers and Electro-Optics Pacific Rim, Optica Publishing Group, 2022
International conference proceedings, 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.

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
International conference proceedings

Enhancement of polarization anisotropy in ultrafast carrier dynamics by intramolecular excitation in the organic conductor κ-(BEDT- TTF)₂Cu(NCS)₂
K. Nakagawa, T. Sato, S. Tsuchiya, J. Yamada, Y. Toda
Europhysics Letters, 136, 5, 57001, 57001, IOP Publishing, 01 Dec. 2021
Scientific journal, Abstract

In this work, in order to investigate the origin of the anomalous polarization dynamics observed in the normal conducting state of the organic superconductor κ-(BEDT-TTF)₂Cu(NCS)₂, we performed optical pump probe measurements by varying the probe pulse energy from $\hbar\omega_{pr} = 1.44$ to 1.59 eV. We found that the polarization-dependent transient signal was most enhanced at ${\sim}1.51\ \text{eV}$ , which was close to the intramolecular excitation energy ${\sim}1.41\ \text{eV}$ of the BEDT-TTF molecules but is not exactly matched. This difference is linked to the formation of an energy gap at the Fermi energy at low temperatures, which results in an increase or decrease in pump-induced absorption between the states near the Fermi energy and the intramolecular excited states depending on probe polarization. In other words, the intramolecular excitation at 1.41 eV, which has a strong polarization dependence, serves as a probe of the dynamics involved in gap formation. A simple calculation shows that the size of the gap is ${\sim}0.20\ \text{eV}$ , which is close to that of the BEDT-TTF based Mott insulators. It is suggested that the gap arises from the phase-separated Mott state caused by photoinduced modulation of effective electron correlation.

Ultrafast dynamics of Mott-state quench and formation in strongly correlated BEDT-TTF molecular conductors observed by three-pulse pump probe spectroscopy
S. Tsuchiya, H. Taniguchi, J. Yamada, Y. Toda, D. Mihailovic, T. Mertelj
Physical Review B, 104, 11, American Physical Society (APS), 24 Sep. 2021, [Peer-reviewed]
Scientific journal

Ultrafast transient reflectivity measurements of optimally doped Bi2+xSr2−xCaCu2O8+δ with disorder
Y. Toda, S. Tsuchiya, M. Oda, T. Kurosawa, S. Katsumata, M. Naseska, T. Mertelj, D. Mihailovic
Physical Review B, 104, 9, 07 Sep. 2021, [Peer-reviewed], [Lead author, Corresponding author]
Scientific journal

Ultrafast Carrier Dynamics in an Organic Superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Br by Spectrally Resolved Pump-Probe Spectroscopy
Satoshi Tsuchiya, Tomaz Mertelj, Dragan Mihailovic, Jun-ichi Yamada, Yasunori Toda
Journal of Superconductivity and Novel Magnetism, 33, 8, 2299, 2303, Aug. 2020, [Peer-reviewed]
English, Scientific journal

Electronic Inhomogeneity in Organic Charge Transfer Salt κ-(BEDT-TTF)2Cu[N(CN)2]I Probed by Polarized Femtosecond Spectroscopy
Satoshi Tsuchiya, Ryota Kuwae, Takumi Kodama, Yusuke Nakamura, Megumi Kurihara, Takashi Yamamoto, Toshio Naito, Yasunori Toda
Journal of the Physical Society of Japan, 89, 6, 064712, 064712, 15 Jun. 2020, [Peer-reviewed]
English, Scientific journal

Polarized Time-Resolved Spectroscopy of Electronic Phase Separation in a Dimer-Mott Organic Insulator
Koichi Nakagawa, Satoshi Tsuchiya, Hiromi Taniguchi, Yasunori Toda
JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM, 33, 2427, 2433, Mar. 2020, [Peer-reviewed]
English, Scientific journal

Laguerre-Gaussian vortex mode generation from astigmatic semiconductor microcavity　　　　　　　　　　　　　　　
K. Nakagawa, K.Yamane, R. Morita, Y. Toda
Appl. Phys. Express, 13, 042001/1, 5, Mar. 2020, [Peer-reviewed]
English, Scientific journal

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
International conference proceedings

Polarization-resolved Ultrafast Spectroscopy in an Organic Mott Insulator kappa-(BEDT-TTF)(2)Cu[N(CN)(2)]Cl
Tsuchiya Satoshi, Nakagawa Koichi, Taniguchi Hiromi, Toda Yasunori
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 88, 7, 15 Jul. 2019, [Peer-reviewed]

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, Jul. 2019, [Peer-reviewed]
English, Scientific journal

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
2019 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2019, Jun. 2019
International conference proceedings

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
2019 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2019, Jun. 2019
International conference proceedings

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
International conference proceedings

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
International conference proceedings

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
International conference proceedings

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
International conference proceedings

Fluctuating superconductivity in kappa-type organic compounds probed by polarized time-resolved spectroscopy
Nakagawa Koichi, Tsuchiya Satoshi, Yamada Jun-ichi, Toda Yasunori
EPL, 122, 6, Jun. 2018, [Peer-reviewed]

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, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
OPTICS EXPRESS, 26, 3, 2584, 2598, Feb. 2018, [Peer-reviewed]
English, Scientific journal

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
International conference proceedings

Generation of arbitrary axisymmetrically polarized pulses with a broadband spectrum
Morita Ryuji, Suzuki Masato, Yamane Keisaku, Oka Kazuhiko, Toda Yasunori
COMPLEX LIGHT AND OPTICAL FORCES XII, 10549, 2018, [Peer-reviewed]
International conference proceedings

Dynamics of superconducting order parameter through ultrafast normal-to-superconducting phase transition in Bi2Sr2CaCu2O8+delta from multipulse polarization-resolved transient optical reflectivity
I. Madan, V. V. Baranov, Y. Toda, M. Oda, T. Kurosawa, V. V. Kabanov, T. Mertelj, D. Mihailovic
PHYSICAL REVIEW B, 96, 18, Nov. 2017, [Peer-reviewed]
English, Scientific journal

Nonequilibrium Quasiparticle Dynamics in Bi-Based Superconductors Measured by Modulation Photoexcitation Spectroscopy
Y. Toda, H. Mochizuki, S. Tsuchiya, T. Kurosawa, M. Oda, T. Mertelj, D. Mihailovic
Journal of Superconductivity and Novel Magnetism, 31, 3, 1, 4, 11 Oct. 2017, [Peer-reviewed]
English, Scientific journal

Photoinduced phase separation with local structural ordering in organic molecular conductors
S. Tsuchiya, K. Nakagawa, J. Yamada, H. Taniguchi, Y. Toda
PHYSICAL REVIEW B, 96, 13, Oct. 2017, [Peer-reviewed]
English, Scientific journal

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, Sep. 2017, [Peer-reviewed]
English, Scientific journal

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), 2017, [Peer-reviewed]
English, International conference proceedings

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, 2017, [Peer-reviewed]
English, International conference proceedings

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, 2017, [Peer-reviewed]
English, International conference proceedings

Snap-shot optical polarization spectroscopy using radially polarized pulses
Kyohhei Shigematsu, Masato Suzuki, Keisaku Yamane, Ryuji Morita, Yasunori Toda
APPLIED PHYSICS EXPRESS, 9, 12, Dec. 2016, [Peer-reviewed]
English, Scientific journal

Pump- and Probe-polarization Analyses of Ultrafast Carrier Dynamics in Organic Superconductors
K. Nakagawa, S. Tsuchiya, J. Yamada, Y. Toda
JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM, 29, 12, 3065, 3069, Dec. 2016, [Peer-reviewed]
English, Scientific journal

Carrier Relaxation Dynamics in the Organic Superconductor kappa-(BEDT-TTF)(2)Cu(NCS)(2) Under Pressure
Satoshi Tsuchiya, Koichi Nakagawa, Jun-ichi Yamada, Yasunori Toda
JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM, 29, 12, 3071, 3074, Dec. 2016, [Peer-reviewed]
English, Scientific journal

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, 26 Oct. 2016

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, Oct. 2016, [Peer-reviewed]
English, Scientific journal

Development of an optical time-resolved measurement system under high-pressure and low-temperature with a piston-cylinder pressure cell
Satoshi Tsuchiya, Yohei Kino, Koichi Nakagawa, Daisuke Nakagawa, Jun-ichi Yamada, Yasunori Toda
REVIEW OF SCIENTIFIC INSTRUMENTS, 87, 4, Apr. 2016, [Peer-reviewed]
English, Scientific journal

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, 15 Jan. 2016

Observation of coherent dynamics of GaN exciton spin excited by Poincare beam pulses
Uchikoga R., Shigematsu K., Yamane K., Morita R., Toda Y.
Meeting Abstracts of the Physical Society of Japan, 71, 1414, 1414, The Physical Society of Japan, 2016
Japanese,

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。

Photoinduced Superconducting Gap and Pseudogap Dynamics in High-T_c Cuprates
Toda Yasunori, Kurosawa Tohru, Oda Migaku
Butsuri, 71, 12, 830, 835, 一般社団法人 日本物理学会, 2016
Japanese, <p>We present polarization and coherent quench analyses of the gap dynamics in Bi-based high-<i>T</i>_c cuprates (Bi2212) using femtosecond optical pump-probe spectroscopy. The polarization analysis has addressed the rotational symmetry breakings of the dynamics, which are suppressed at room temperature and appears below <i>T</i>^*. The coherent quench experiment of the pseudogap has indicated an absence of long-range electronic order beyond a few coherence lengths on short timescales.</p>

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, Jan. 2016, [Peer-reviewed]
English, Scientific journal

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, Dec. 2015
English, Scientific journal

Time-resolved polarimetry for photoexcited QP dynamics in Bi2212
K. Watanabe, S. Tsuchiya, Y. Toda, T. Kurosawa, M. Oda, T. Mertelj, I. Madan, V. V. Kabanov, D. Mihailovic
INTERNATIONAL JOURNAL OF MODERN PHYSICS B, 29, 25-26, Oct. 2015, [Peer-reviewed]
English, Scientific journal

Symmetry-dependent carrier relaxation dynamics and charge-density-wave transition in DyTe3 probed by polarized femtosecond spectroscopy
S. Tsuchiya, Y. Sugawara, S. Tanda, Y. Toda
JOURNAL OF OPTICS, 17, 8, Aug. 2015, [Peer-reviewed]
English, Scientific journal

Evidence for carrier localization in the pseudogap state of cuprate superconductors from coherent quench experiments
I. Madan, T. Kurosawa, Y. Toda, M. Oda, T. Mertelj, D. Mihailovic
NATURE COMMUNICATIONS, 6, Apr. 2015, [Peer-reviewed]
English, Scientific journal

Extended Stokes parameters for cylindrically polarized beams
Masato Suzuki, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
OPTICAL REVIEW, 22, 1, 179, 183, Feb. 2015, [Peer-reviewed]
English, Scientific journal

17aCF-5 Photoexcited quasiparticle dynamics in the pseudogap state of high-Tc superconductors
Toda Yasunori
Meeting Abstracts of the Physical Society of Japan, 70, 1210, 1211, The Physical Society of Japan (JPS), 2015
Japanese

22pBH-3 Azimuthal Doppler Shift in Saturated Absorption Spectroscopy Using an Optical Vortex Laser
Aramaki M., Yoshimura S., Morisaki T., Terasaka K., Toda Y., Tanaka M.
Meeting Abstracts of the Physical Society of Japan, 70, 875, 875, The Physical Society of Japan (JPS), 2015
Japanese

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), 2015, [Peer-reviewed]
English, International conference proceedings

Spatiotemporal coherent spectroscopy using singular optical pulses
TODA YASUNORI, SHIGEMATSU KYOHHEI
Proc Hiroshima Int Symp Synchrotron Radiat, 19th, 116, 120, 2015
English

Unified understanding of the electron-phonon coupling strength for nanocarbon allotropes
S. Ono, Y. Toda, J. Onoe
Physical Review B, 90, 155435, Nov. 2014, [Peer-reviewed]
English, Scientific journal

Unified understanding of the electron-phonon coupling strength for nanocarbon allotropes
Shota Ono, Yasunori Toda, Jun Onoe
PHYSICAL REVIEW B, 90, 15, 155435.1-155435.5, Oct. 2014, [Peer-reviewed]
English, Scientific journal

Rotational symmetry breaking in Bi2Sr2CaCu2O8+delta probed by polarized femtosecond spectroscopy
Y. Toda, F. Kawanokami, T. Kurosawa, M. Oda, I. Madan, T. Mertelj, V. V. Kabanov, D. Mihailovic
PHYSICAL REVIEW B, 90, 9, Sep. 2014
English, Scientific journal

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, 21 Jul. 2014
English, International conference proceedings

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, 21 Jul. 2014
English, International conference proceedings

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, Jul. 2014
English, Scientific journal

Separating pairing from quantum phase coherence dynamics above the superconducting transition by femtosecond spectroscopy
I. Madan, T. Kurosawa, Y. Toda, M. Oda, T. Mertelj, P. Kusar, D. Mihailovic
SCIENTIFIC REPORTS, 4, Jul. 2014
English, Scientific journal

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, May 2014, [Peer-reviewed]
English, Scientific journal

Strain-Induced Enhancement of the Electron Energy Relaxation in Strongly Correlated Superconductors
C. Gadermaier, V. V. Kabanov, A. S. Alexandrov, L. Stojchevska, T. Mertelj, C. Manzoni, G. Cerullo, N. D. Zhigadlo, J. Karpinski, Y. Q. Cai, X. Yao, Y. Toda, M. Oda, S. Sugai, D. Mihailovic
PHYSICAL REVIEW X, 4, 1, 011056, Mar. 2014, [Peer-reviewed]
English, Scientific journal

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
English, International conference proceedings

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
English, International conference proceedings

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
English, International conference proceedings

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), 2014, [Peer-reviewed]
English, International conference proceedings

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), 2014, [Peer-reviewed]
English, International conference proceedings

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, 2014
English, International conference proceedings

Impact of pseudogap on photoinduced superconducting phase transition in underdoped Bi2212
Y. Toda, T. Mertelj, P. Kusar, T. Kurosawa, M. Oda, M. Ido, D. Mihailovic
PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS, 493, 112, 113, Oct. 2013, [Peer-reviewed]
English, Scientific journal

Exciton-Exciton Interactions in Tensile-Strained GaN
Yasunori Toda, Kyohhei Shigematsu, Akira Hasegawa, Satoru Adachi
JAPANESE JOURNAL OF APPLIED PHYSICS, 52, 8, 08JL03, Aug. 2013, [Peer-reviewed]
English, Scientific journal

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, 08JL08, Aug. 2013, [Peer-reviewed]
English, Scientific journal

Revealing the anomalous nonequilibrium carrier relaxation dynamics in C60-related materials
Shota Ono, Hiroyuki Shima, Yasunori Toda
Trans. Mater. Res. Soc. Jpn., 38, 2, 283, 286, The Materials Research Society of Japan, Jun. 2013, [Peer-reviewed]
English, Scientific journal, We theoretically demonstrate that the temperature (T)-dependence of photo-excited carrier relaxation time (τ) in energy-gapped systems strongly depends on the rate of energy transfer from a longitudinal to transverse acoustic phonon mode. By considering the anharmonic coupling between them, we resolve an ambiguity in how to interpret the T-dependence of τ in alkali-doped C₆₀ superconductors.

Direct observation and interpretation of carrier dynamics of molecular magnetic superconductors
T. Naito, S. Matsuo, T. Inabe, Y. Toda
Journal of Superconductivity and Novel Magnetism, 26, 5, 1679, 1682, Springer New York LLC, 2013, [Peer-reviewed]
English, Scientific journal

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, [Peer-reviewed]
English, Scientific journal

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), 2013, [Peer-reviewed]
English, International conference proceedings

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), 2013, [Peer-reviewed]
English, International conference proceedings

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), 2013, [Peer-reviewed]
English, International conference proceedings

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), 2013, [Peer-reviewed]
English, International conference proceedings

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, [Peer-reviewed]
English, International conference proceedings

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, [Peer-reviewed]
English, International conference proceedings

Direct observation and interpretation of carrier dynamics of molecular magnetic superconductors
T. Naito, S. Matsuo, T. Inabe, Y. Toda
Journal of Superconductivity and Novel Magnetism, 26, 5, 1679, 1682, Springer New York LLC, 2013
English, Scientific journal

Observation of Riemannian geometric effects on electronic states
J. Onoe, T. Ito, H. Shima, Y. Toda, H. Yoshioka, S. Kimura
Europhysics Letters, 98, 2, 27001, 27 Sep. 2012, [Peer-reviewed]
English, Scientific journal

Theory of photoexcited carrier relaxation across the energy gap of phase-ordered materials
Shota Ono, Hiroyuki Shima, Yasunori Toda
PHYSICAL REVIEW B, 86, 10, 104512, Sep. 2012, [Peer-reviewed]
English, Scientific journal

Ultrashort optical-vortex pulse generation in few-cycle regime
Keisaku Yamane, Yasunori Toda, Ryuji Morita
OPTICS EXPRESS, 20, 17, 18986, 18993, Aug. 2012, [Peer-reviewed]
English, Scientific journal

High superconducting critical temperatures depend systematically on the electron-phonon interaction strength
C. Gadermaier, V. V. Kabanov, A. S. Alexandrov, L. Stojchevska, T. Mertelj, C. Manzoni, G. Cerullo, N. D. Zhigadlo, J. Karpinski, Y. Q. Cai, X. Yao, Y. Toda, M. Oda, S. Sugai, D. Mihailovic
May 2012, [Peer-reviewed]
Scientific journal, The origin of high critical temperature (Tc) superconductivity is still

remarkably elusive. To gain insight into the high- Tc mechanism, we need

experiments which identify the parameters that determine Tc and link them to

the interaction(s) that establish the superconducting state. Here we show that

for pnictides, cuprates, and bismuthates Tc depends systematically on the

primary electron energy relaxation rate 1/tau_1. We find that 1/tau_1 is a

direct experimental measure of the strength of the electron-phonon interaction

(EPI) and correlates with structural parameters, in particular the l...

Unifying explanation for carrier relaxation anomaly in gapped systems
Shota Ono, Hiroyuki Shima, Yasunori Toda
Feb. 2012, [Peer-reviewed]
Scientific journal, We develop a theory to describe energy relaxation of photo-excited carriers

in low-temperature ordered states with band gap opening and formulate carrier

relaxation time $\tau$ near and below transition temperature $T_{\mathrm{c } }$

by quantifying contributions from different carrier-phonon scatterings to the

relaxation rate. The theory explains anomalous experimental observations of

$\tau$ in gapped systems. Transverse acoustic (TA) phonon modes play a crucial

role in carrier relaxation; their heat capacity determines $\tau$-divergence

near $T_{\mathrm{c } }$. The theory is validated by fitti...

Theory of photoexcited carrier relaxation across the energy gap of phase-ordered materials
Shota Ono, Hiroyuki Shima, Yasunori Toda
Phys. Rev. B, 86, 10, 104512, 2012, [Peer-reviewed]

One-Dimensional Uneven Peanut-Shaped C-60 Polymer: A Quantum Electronic System in Riemannian Space
Jun Onoe, Takahiro Ito, Shin-Ichi Kimura, Hiroyuki Shima, Yasunori Toda, Hideo Yoshioka
FULLERENES NANOTUBES AND CARBON NANOSTRUCTURES, 20, 1, 1, 16, 2012, [Peer-reviewed]
English, Scientific journal

Carrier Dynamics in a Series of Organic Magnetic Superconductors
Toshio Naito, Saori Matsuo, Tamotsu Inabe, Yasunori Toda
JOURNAL OF PHYSICAL CHEMISTRY C, 116, 3, 2588, 2593, Jan. 2012, [Peer-reviewed]
English, Scientific journal

One-dimensional uneven peanut-shaped C60 polymer: a quantum electronic system on Riemannian space
J. Onoe, T. Ito, S. Kimura, H. Shima, Y. Toda, H. Yoshioka
Fullerene, Nanotubes, and Carbon Nanostructures, 20, 1, 1-16, 2012, [Peer-reviewed], [Invited]
English, Scientific journal

Generation of Optical Pulses with Phase and/or Polarization Singularities and Their Applications
MORITA Ryuji, TODA Yasunori, OMATSU Takashige
J. Surf. Sci. Soc. Jpn., 32, 12, 748, 754, The Surface Science Society of Japan, 10 Dec. 2011
Japanese, Together with the introduction of topological light waves (light with phase or polarization singularities), their generation and applications were described. Using a photonic crystal, axially-symmetric polarizer or mirror, 1) supercontinuum optical vortex generation ranging ∼500 to ∼800 nm without spatial nor topological-charge dispersions, 2) generation of ultrabroadband axially-symmetric polarization modes ranging ∼600 to ∼800 nm without polarization dispersion, and 3) a high power radially-polarized light generation directly from a diode-pumped Nd:YVO₄ bounce amplifier were experimentally demonstrated. As applications of generated topological light waves, 4) laser ablation of Ta plates using nanosecond optical vortex pulses and, in particular, using spin-orbit interactions of light, microneedle fabrication on a metal surface by laser ablation were performed.

Quasiparticle relaxation dynamics in underdoped Bi2Sr2CaCu2O8+delta by two-color pump-probe spectroscopy
Y. Toda, T. Mertelj, P. Kusar, T. Kurosawa, M. Oda, M. Ido, D. Mihailovic
PHYSICAL REVIEW B, 84, 17, 174516, Nov. 2011, [Peer-reviewed]
English, Scientific journal

Femtosecond Carrier Relaxation Dynamics and Photoinduced Phase Separation in kappa-(BEDT-TTF)(2)Cu[N(CN)(2)]X (X = Br; Cl)
Y. Toda, T. Mertelj, T. Naito, D. Mihailovic
PHYSICAL REVIEW LETTERS, 107, 22, 227002, Nov. 2011, [Peer-reviewed]
English, Scientific journal

Mechanisms of nonthermal destruction of the superconducting state and melting of the charge-density-wave state by femtosecond laser pulses
L. Stojchevska, P. Kusar, T. Mertelj, V. V. Kabanov, Y. Toda, X. Yao, D. Mihailovic
PHYSICAL REVIEW B, 84, 18, 180507, Nov. 2011, [Peer-reviewed]
English, Scientific journal

Quasiparticle relaxation dynamics in underdoped Bi2Sr2CaCu2O8+delta by two-color pump-probe spectroscopy
Y. Toda, T. Mertelj, P. Kusar, T. Kurosawa, M. Oda, M. Ido, D. Mihailovic
PHYSICAL REVIEW B, 84, 17, 174516, Nov. 2011, [Peer-reviewed]
English, Scientific journal

Effects of inter-molecular charge-transfer excitons on the external quantum efficiency of zinc-porphyrin/C-60 heterojunction photovoltaic cells
Sou Ryuzaki, Toshihiro Kai, Yasunori Toda, Satoru Adachi, Jun Onoe
JOURNAL OF PHYSICS D-APPLIED PHYSICS, 44, 14, 145103, Apr. 2011, [Peer-reviewed]
English, Scientific journal

Nonlinear propagation effects on high-power optical-vortex pulses in anisotropic crystals
Masato Suzuki, Yasunori Toda, Ryuji Morita
2011 Conference on Lasers and Electro-Optics Europe and 12th European Quantum Electronics Conference, CLEO EUROPE/EQEC 2011, 2011, [Peer-reviewed]
English, International conference proceedings

Time-resolved polarimetry for photoexcited QP dynamics in Bi2212
K. Watanabe, S. Tsuchiya, Y. Toda, T. Kurosawa, M. Oda, T. Mertelj, I. Madan, V. V. Kabanov, D. Mihailovic
Int. J. Mod. Phys. B 29, 1542031(1-7) (2015), 29, 1542031, 2011, [Peer-reviewed]
English

Infrared phonon anomaly of one-dimensional metallic peanut-shaped C-60 polymer
J. Onoe, A. Takashima, Y. Toda
APPLIED PHYSICS LETTERS, 97, 24, 241911, Dec. 2010, [Peer-reviewed]
English, Scientific journal

Chiral Charge-Density Waves
J. Ishioka, Y. H. Liu, K. Shimatake, T. Kurosawa, K. Ichimura, Y. Toda, M. Oda, S. Tanda
PHYSICAL REVIEW LETTERS, 105, 17, 176401-1, 176401-4, Oct. 2010, [Peer-reviewed]
English, Scientific journal

Chiral Charge-Density Waves
J. Ishioka, Y. H. Liu, K. Shimatake, T. Kurosawa, K. Ichimura, Y. Toda, M. Oda, S. Tanda
PHYSICAL REVIEW LETTERS, 105, 17, Oct. 2010, [Peer-reviewed]
English, Scientific journal

Dynamics of a paired optical vortex generated by second-harmonic generation
Y. Toda, S. Honda, R. Morita
OPTICS EXPRESS, 18, 17, 17796, 17804, Aug. 2010, [Peer-reviewed]
English, Scientific journal

Nonequilibrium Carrier Dynamics Studied in Underdoped Bi2212 by Polarized Optical Pump-Probe Spectroscopy
Y. Toda, J. Sekiya, Y. H. Liu, N. Momono, M. Oda, M. Ido
JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM, 23, 5, 871, 872, Jul. 2010, [Peer-reviewed]
English, Scientific journal

Time-resolved optical study on BETS superconductors and related salts
T. Naito, M. Fukusaku, S. Matsuo, K. Tajima, T. Inabe, Y. Toda
PHYSICA B-CONDENSED MATTER, 405, 11, S269, S272, Jun. 2010, [Peer-reviewed]
English, Scientific journal

Measurement of chirality of charge-density-waves in TiSe2 by using STM
J. Ishioka, Y. H. Liu, K. Shimatake, T. Kurosawa, K. Ichimura, Y. Toda, M. Oda, S. Tanda
PHYSICA B-CONDENSED MATTER, 405, 11, S214, S216, Jun. 2010, [Peer-reviewed]
English, Scientific journal

Carrier dynamics in an organic magnetic superconductor and related salts kappa, lambda-(BETS)(2)MCl4 (M = Fe, Ga)
T. Naito, S. Matsuo, T. Inabe, Y. Toda
JOURNAL OF PHYSICS-CONDENSED MATTER, 22, 18, 185701-1, 185701-7, May 2010, [Peer-reviewed]
English, Scientific journal

Demonstration of spatial mode division multiplexing using Laguerre-Gaussian mode beam in telecom-wavelength
Yoshinari Awaji, Naoya Wada, Yasunori Toda
2010 23rd Annual Meeting of the IEEE Photonics Society, PHOTINICS 2010, 551, 552, 2010, [Peer-reviewed]
English, International conference proceedings

Real Space Mapping of Exciton Interaction Strength in GaN Films by using Four-Wave-Mixing Technique
S. Adachi, Y. Toda
J. Vac. Soc. Jpn., 53, 6, 387, 392, The Vacuum Society of Japan, 2010, [Peer-reviewed], [Invited]
Japanese, By using four-wave-mixing technique, we demonstrated the possibility of the real space mapping of exciton-exciton interaction and strain in GaN films grown on various substrates. The image obtained from the evaluation of the quantum beats indicates that these reductions correspond to the phase changes between two exciton transitions, reflecting the spatial properties of exciton-exciton interactions. The line-localization suggests a contribution of line-defect to the anomalous interactions.

Infrared phonon anomaly of one-dimensional metallic peanut-shaped C60 polymer
J. Onoe, A. Takashima, Y. Toda
Appl. Phys. Lett., 97, 241911, 2010, [Peer-reviewed]
English, Scientific journal

Global evaluation of closed-loop electron dynamics in quasi-one-dimensional conductors using polarization vortices
Yu Tokizane, Katsuhiro Shimatake, Yasunori Toda, Kazuhiko Oka, Masakatsu Tsubota, Satoshi Tanda, Ryuji Morita
OPTICS EXPRESS, 17, 26, 24198, 24207, Dec. 2009, [Peer-reviewed]
English, Scientific journal

Coherent Dynamics of Exciton Fine Structure in Uniaxially-Strained GaN
Tetsuro Ishiguro, Yasunori Toda, Satoru Adachi
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 78, 10, 174018-1, 4, Oct. 2009, [Peer-reviewed]
English, Scientific journal

Coherent transfer of orbital angular momentum to excitons by optical four-wave mixing
Y. Ueno, Y. Toda, S. Adachi, R. Morita, T. Tawara
OPTICS EXPRESS, 17, 22, 20567, 20574, Oct. 2009, [Peer-reviewed]
English, Scientific journal

Optical selection of a multiple phase order in the charge density wave condensate o-TaS3 using a spectrally resolved nonequilibrium measurement
Y. Toda, R. Onozaki, M. Tsubota, K. Inagaki, S. Tanda
PHYSICAL REVIEW B, 80, 12, 121103, Sep. 2009, [Peer-reviewed]
English, Scientific journal

Generation and Spatiotemporal Evolution of Optical Vortices in Femtosecond Laser Pulses
Yasunori Toda, Koshi Nagaoka, Katsuhiro Shimatake, Ryuji Morita
ELECTRICAL ENGINEERING IN JAPAN, 167, 4, 39, 46, Jun. 2009, [Peer-reviewed]
English, Scientific journal

Pump-probe measurement of closed loop coherence in a quasi one-dimensional ring crystal using polarization vortex
Yu Tokizane, Katsuhiro Shimatake, Yasunori Toda, Kazuhiko Oka, Masakatsu Tsubota, Satoshi Tanda, Ryuji Morita
The European Conference on Lasers and Electro-Optics (CLEO/Europe) 2009, Jun. 2009, [Peer-reviewed]
English, International conference proceedings, Electron in a quasi one-dimensional NbSe3 whisker crystal form a collective state at low temperature. It is called charge density wave (CDW) state. Under certain condition, NbSe3 grows as a ring crystal with closed loop structure [1]. This kind of global structural change brings an effect on a formation of the collective state [2]. For observation of a global electronic property on the entire ring crystal, it is necessary to apply a probe method appropriate for the closed loop structure of a ring crystal. The light with a polarization of a closed loop structure, called a polarization vortex, is appropriate for this measurement.

Four-wave-mixing study of exciton fine structure in GaN
T. Ishiguro, Y. Toda, S. Adachi, K. Tadatomo, K. Hoshino
PHYSICA STATUS SOLIDI C - CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 6, NO 1, 6, 1, 42, +, 2009, [Peer-reviewed]
English, International conference proceedings

Study on dephasing dynamics of Exciton Fine Structure in GaN
T. Ishiguro, Y. Toda, S. Adachi, S. F. Chichibu
PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 6, SUPPL 2, 6, S719, S722, 2009, [Peer-reviewed]
English, International conference proceedings

Spatial properties of exciton-exciton interactions in GaN observed by four-wave-mixing spectroscopy
Y. Toda, K. Yamaguchi, T. Ishiguro, K. Hoshino, K. Tadatomo, S. Adachi
PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 6, SUPPL 2, 6, S684, S686, 2009, [Peer-reviewed]
English, International conference proceedings

Femtosecond carrier dynamics in quasi-one-dimensional topological compounds
Y. Toda, K. Shimatake, S. Tanda, J. Onoe
ULTRAFAST PHENOMENA IN SEMICONDUCTORS AND NANOSTRUCTURE MATERIALS XIII, 7214, 2009
English, International conference proceedings

Direct observation of the coexistence of the pseudogap and superconducting quasiparticles in Bi2Sr2CaCu2O8+y by time-resolved optical spectroscopy
Y. H. Liu, Y. Toda, K. Shimatake, N. Momono, M. Oda, M. Ido
PHYSICAL REVIEW LETTERS, 101, 13, 137003, Sep. 2008, [Peer-reviewed]
English, Scientific journal

Carrier dynamics in kappa-type organic superconductors: Time-resolved observation
Toshio Naito, Yukari Yamada, Tamotsu Inabe, Yasunori Toda
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 77, 6, 064709-1, 064709-6, Jun. 2008, [Peer-reviewed]
English, Scientific journal

Highly sensitive optical probe for uniaxial strain in GaN epitaxial films
Y. Toda, T. Ishiguro, S. Adachi, K. Hoshino, K. Tadatomo
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, 245, 5, 878, 880, May 2008, [Peer-reviewed]
English, Scientific journal

Femtosecond carrier dynamics in electron-beam-irradiated C-60 film
Y. Toda, S. Ryuzaki, J. Onoe
APPLIED PHYSICS LETTERS, 92, 9, 094102, Mar. 2008, [Peer-reviewed]
English, Scientific journal

Dephasing studies of exciton fine structure in uniaxially-strained GaN
T. Ishiguro, Y. Toda, S. Adachi, K. Hoshino, Y. Arakawa
PHYSICA STATUS SOLIDI C - CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 5, NO 6, 5, 6, 2114, +, 2008, [Peer-reviewed]
English, International conference proceedings

Four-wave mixing spectroscopy of ultraviolet excitons in strained GaN
T. Ishiguro, Y. Toda, S. Adachi, S. F. Chichibu
ULTRAFAST PHENOMENA IN SEMICONDUCTORS AND NANOSTRUCTURE MATERIALS XII, 6892, 2008
English, International conference proceedings

Selective optical probing of the charge-density-wave phases in NbSe3
K. Shimatake, Y. Toda, S. Tanda
PHYSICAL REVIEW B, 75, 11, 115120, Mar. 2007, [Peer-reviewed]
English, Scientific journal

Coherent double-pulse excitation of charge-density-wave oscillation
Tatsuyuki Onozaki, Yasunori Toda, Satoshi Tanda, Ryuji Morita
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS, 46, 2, 870, 872, Feb. 2007, [Peer-reviewed]
English, Scientific journal

Time-resolved four-wave mixing studies of excitons in GaN
K. Yamaguchi, Y. Toda, T. Ishiguro, S. Adachi, K. Hoshin, K. Tadatomo
PHYSICA STATUS SOLIDI C - CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 4 NO 7 2007, 4, 7, 2752, +, 2007, [Peer-reviewed]
English, International conference proceedings

Coherent manipulation of A and B excitons in GaN
T. Ishiguro, Y. Toda, S. Adachi, K. Hazu, T. Sota, S. F. Chichibu
PHYSICA STATUS SOLIDI C - CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 4 NO 7 2007, 4, 7, 2776, +, 2007, [Peer-reviewed]
English, International conference proceedings

Exciton spin relaxation in GaN observed by spin grating experiment
T. Ishiguro, Y. Toda, S. Adachi
APPLIED PHYSICS LETTERS, 90, 1, 11904, Jan. 2007, [Peer-reviewed]
English, Scientific journal

Generation and spatio-temporal evolution of optical vortices in femtosecond laser pulses
Yasunori Toda, Koshi Nagaoka, Katsuhiro Shimatake, Ryuji Morita
IEEJ Transactions on Electronics, Information and Systems, 127, 9, 4, 1313, Institute of Electrical Engineers of Japan, 2007
English, Scientific journal

Degenerate four-wave mixing spectroscopy of GaN films on various substrates
T Ishiguro, Y Toda, S Adachi, T Mukai, K Hoshino, Y Arakawa
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, 243, 7, 1560, 1563, Jun. 2006, [Peer-reviewed]
English, Scientific journal

Transient pump-probe measurements for polarized excitons in strained GaN epitaxial layers
T Ishiguro, Y Toda, S Adachi, M Arita, Y Arakawa
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, 243, 7, 1564, 1567, Jun. 2006, [Peer-reviewed]
English, Scientific journal

Four-wave mixing measurements of biexcitons in uniaxially-strained GaN films
Satoru Adachi, Yasunori Toda, Tetsuro Ishiguro
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, 243, 7, 1568, 1571, Jun. 2006, [Peer-reviewed]
English, Scientific journal

Quenching of phase coherence in quasi-one-dimensional ring crystals
K Shimatake, Y Toda, S Tanda
PHYSICAL REVIEW B, 73, 15, 153403, Apr. 2006, [Peer-reviewed]
English, Scientific journal

Ultrafast single particle dynamics in quasi-one-dimensional NbSe 3 studied by two-color pump-probe experiments
K. Shimatake, Y. Toda, S. Tanda
Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference, CLEO/QELS 2006, 2006, [Peer-reviewed]
English, International conference proceedings

In-plane anisotropy in uniaxially-strained GaN films detected by optical diffraction technique
Satoru Adachi, Yasunori Toda, Tetsuro Ishiguro, Katsuyuki Hoshino, Yasuhiko Arakawa
PHYSICA STATUS SOLIDI C - CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 3, NO 6, 3, 6, 1595, 1598, 2006
English, International conference proceedings

Coherent collective oscillation in the commensurate phase of the TaS3 compound
T Minami, Y Toda, K Shimatake, S Tanda
JOURNAL DE PHYSIQUE IV, 131, 121, 122, Dec. 2005, [Peer-reviewed]
English, Scientific journal

Ultrafast optical study of the CDW phase transition in topological crystals
K Shimatake, Y Toda, T Minami, S Tanda
JOURNAL DE PHYSIQUE IV, 131, 295, 298, Dec. 2005, [Peer-reviewed]
English, Scientific journal

Optical diffraction spectroscopy of excitons in uniaxially strained GaN films
Y Toda, S Adachi, Y Abe, K Hoshino, Y Arakawa
PHYSICAL REVIEW B, 71, 19, 195315, May 2005, [Peer-reviewed]
English, Scientific journal

Spectrally-resolved nonlinear spectroscopy of in-plane anistropy in uniaxally-starined GaN epilayers
S Adachi, Y Toda
PHYSICA STATUS SOLIDI C - CONFERENCES AND CRITICAL REVIEWS, VOL. 2 , NO 11, 2, 11, 3936, 3940, 2005, [Peer-reviewed]
English, International conference proceedings

Three-dimensional imaging of GaN films using transient two-photon absorption excited by near-infrared laser pulses
Y Abe, Y Toda, K Hoshino, Y Arakawa
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS, 44, 16-19, L535, L538, 2005, [Peer-reviewed]
English, Scientific journal

Spectrally-resolved nonlinear spectroscopy of in-plane anisotropy in uniaxially-strained GaN epilayers
Satoru Adachi, Yasunori Toda
Physica Status Solidi C: Conferences, 2, 11, 3936, 3940, 2005, [Peer-reviewed]
English, International conference proceedings

Coherent optical control of molecular motion using polarized sequential pulses
K Itoh, Y Toda, R Morita, M Yamashita
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 43, 9A, 6448, 6451, Sep. 2004, [Peer-reviewed]
English, Scientific journal

Anomalous coherent phonon oscillations in the commensurate phase of the quasi-two-dimensional 1T-TaS2 compound
Y. Toda, K. Tateishi, S. Tanda
Physical Review B - Condensed Matter and Materials Physics, 70, 3, 1, 33106, Jul. 2004, [Peer-reviewed]
English, Scientific journal

Anomalous coherent phonon oscillations in the commensurate phase of the quasi-two-dimensional 1T-TaS2 compound
Y Toda, K Tateishi, S Tanda
PHYSICAL REVIEW B, 70, 3, Jul. 2004, [Peer-reviewed]
English, Scientific journal

Selective excitation of self-assembled quantum dots by using shaped pulse
Y Toda, T Nakaoka, R Morita, M Yamashita, T Inoue, Y Arakawa
PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES, 21, 2-4, 180, 183, Mar. 2004, [Peer-reviewed]
English, Scientific journal

Two-photon absorption and multiphoton-induced photoluminescence of bulk GaN excited below the middle of the band gap
Y Toda, T Matsubara, R Morita, M Yamashita, K Hoshino, T Someya, Y Arakawa
APPLIED PHYSICS LETTERS, 82, 26, 4714, 4716, Jun. 2003, [Peer-reviewed]
English, Scientific journal

Efficient two-photon absorption of bulk GaN in the near-infrared region
Y Toda, T Matsubara, R Morita, K Hoshino, T Someya, Y Arakawa
5TH INTERNATIONAL CONFERENCE ON NITRIDE SEMICONDUCTORS (ICNS-5), PROCEEDINGS, 0, 7, 2627, 2630, 2003, [Peer-reviewed]
English, International conference proceedings

Raman study of the strain in GaN films by comparison with a free-standing GaN
T Inoue, Y Toda, K Hoshino, T Someya, Y Arakawa
5TH INTERNATIONAL CONFERENCE ON NITRIDE SEMICONDUCTORS (ICNS-5), PROCEEDINGS, 0, 7, 2428, 2431, 2003, [Peer-reviewed]
English, International conference proceedings

Optical characterization of strong carrier-phonon interactions in single quantum dots
Y. Toda, T. Inoue, T. Nakaoka, S. Ishida, Y. Arakawa
Pacific Rim Conference on Lasers and Electro-Optics, CLEO - Technical Digest, 2, 448, Institute of Electrical and Electronics Engineers Inc., 2003, [Peer-reviewed]
English, International conference proceedings

Efficient two-photon absorption of bulk GaN in the near-infrared region
Y. Toda, T. Matsubara, R. Morita, K. Hoshino, T. Someya, Y. Arakawa
Physica Status Solidi C: Conferences, 7, 2627, 2630, 2003, [Peer-reviewed]
English, International conference proceedings

Raman study of the strain in GaN films by comparison with a free-standing GaN
T. Inoue, Y. Toda, K. Hoshino, T. Someya, Y. Arakawa
Physica Status Solidi C: Conferences, 7, 2428, 2431, 2003, [Peer-reviewed]
English, International conference proceedings

Line broadening of photoluminescence excitation resonances in single self-assembled quantum dots
Y Toda, S Kako, M Nishioka, Y Arakawa
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS, 41, 12B, L1464, L1466, Dec. 2002, [Peer-reviewed]
English, Scientific journal

Observation of dip structures in PLE spectra of a highly excited single self-assembled quantum dot
S. Kako, T. Sugimoto, Y. Toda, S. Ishida, M. Nishioka, Y. Arakawa
Physica E: Low-Dimensional Systems and Nanostructures, 13, 2-4, 151, 154, 2002, [Peer-reviewed]
English, Scientific journal

Quantum interference due to continuum states in single self-assembled quantum dots
Y. Toda, M. Takahashi, T. Sugimoto, M. Nishioka, S. Ishida, Y. Arakawa
Technical Digest - Summaries of Papers Presented at the Quantum Electronics and Laser Science Conference, QELS 2001, 20, 21, Institute of Electrical and Electronics Engineers Inc., 2001, [Peer-reviewed]
English, International conference proceedings

Resonant Raman scattering of optical phonons in self-assembled quantum dots
Y Toda, O Moriwaki, M Nishioka, Y Arakawa
PHYSICA E, 8, 4, 328, 332, Dec. 2000, [Peer-reviewed]
English, Scientific journal

Near-field coherent excitation spectroscopy of InGaAs/GaAs self-assembled quantum dots
Y Toda, T Sugimoto, M Nishioka, Y Arakawa
APPLIED PHYSICS LETTERS, 76, 26, 3887, 3889, Jun. 2000, [Peer-reviewed]
English, Scientific journal

Near-field spectroscopy of a single InGaAs self-assembled quantum dot
Y Toda, Y Arakawa
IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS, 6, 3, 528, 533, May 2000, [Peer-reviewed], [Invited]
English, Scientific journal

Near-field spectroscopy of single self-assembled InAs quantum dots: Observation of energy relaxation process
Y Toda, K Suzuki, S Shinomori, Y Arakawa
MICROELECTRONIC ENGINEERING, 47, 1-4, 111, 113, Jun. 1999, [Peer-reviewed]
English, Scientific journal

Efficient carrier relaxation mechanism in InGaAs GaAs self-assembled quantum dots based on the existence of continuum states
Y Toda, O Moriwaki, M Nishioka, Y Arakawa
PHYSICAL REVIEW LETTERS, 82, 20, 4114, 4117, May 1999, [Peer-reviewed]
English, Scientific journal

Polarized photoluminescence spectroscopy of single self-assembled InAs quantum dots
Y Toda, S Shinomori, K Suzuki, Y Arakawa
PHYSICAL REVIEW B, 58, 16, R10147, R10150, Oct. 1998, [Peer-reviewed]
English, Scientific journal

Near-field magneto-optical spectroscopy of single self-assembled InAs quantum dots
Y Toda, S Shinomori, K Suzuki, Y Arakawa
APPLIED PHYSICS LETTERS, 73, 4, 517, 519, Jul. 1998, [Peer-reviewed]
English, Scientific journal

Near-field spectroscopy of quantum wires grown by selective growth method
Y Toda, S Shinomori, T Arakawa, Y Arakawa
PHYSICA E, 2, 1-4, 987, 990, Jul. 1998, [Peer-reviewed]
English, Scientific journal

Near-field optical spectroscopy of selfassembled quantum dots: NSOM apparatus for measuring the features of single dots
Y Toda, S Shinomori, K Suzuki, Y Arakawa
SOLID-STATE ELECTRONICS, 42, 7-8, 1083, 1086, Jul. 1998, [Peer-reviewed]
English, Scientific journal

Polarized photo-luminescence spectroscopy of single self-assembled InAs quantum dots
Y. Toda, S. Shinomori, K. Suzuki, Y. Arakawa
Physical Review B, 58, 16, R10147, R10150, American Physical Society (APS), 1998, [Peer-reviewed]
Scientific journal

Polarized photoluminescence spectroscopy of single self-assembled InAs quantum dots
Y. Toda, S. Shinomori, K. Suzuki, Y. Arakawa
Physical Review B - Condensed Matter and Materials Physics, 58, 16, R10147, R10150, 1998, [Peer-reviewed]
English, Scientific journal

Spectroscopy of a single quantum dot by NSOM for photonic device applications
Y Arakawa, Y Toda, S Shinomori
PHYSICS AND SIMULATION OF OPTOELECTRONIC DEVICES VI, PTS 1 AND 2, 3283, 785, 792, 1998, [Peer-reviewed]
English, International conference proceedings

Spatially and spectrally resolved imaging of GaAs quantum-dot structures using near-field optical technique
Y Toda, M Kourogi, M Ohtsu, Y Nagamune, Y Arakawa
APPLIED PHYSICS LETTERS, 69, 6, 827, 829, Aug. 1996, [Peer-reviewed]
English, Scientific journal

HIGH-SPATIAL-RESOLUTION DIAGNOSTICS OF OPTICAL WAVE-GUIDES USING A PHOTON-SCANNING TUNNELING MICROSCOPE
Y TODA, M OHTSU
IEEE PHOTONICS TECHNOLOGY LETTERS, 7, 1, 84, 86, Jan. 1995, [Peer-reviewed]
English, Scientific journal

FREQUENCY STABILIZATION OF 1.5-MU-M DIODE-LASER USING NONLINEAR-OPTICAL FREQUENCY-CONVERSION IN ORGANIC FIBER
Y TODA, T ENAMI, M OUTSU
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS, 32, 9A, L1233, L1235, Sep. 1993, [Peer-reviewed]
English, Scientific journal

1.5 MU-M DIODE LASER-BASED NONLINEAR FREQUENCY CONVERSIONS BY USING POTASSIUM TITANYL PHOSPHATE
WZ WANG, K NAKAGAWA, Y TODA, M OHTSU
APPLIED PHYSICS LETTERS, 61, 16, 1886, 1888, Oct. 1992, [Peer-reviewed]
English, Scientific journal

Study of charge glass in θ-(BEDT-TTF)₂CsCo(SCN)₄ probed by pump-probe spectroscopy with different probe polarizations
和田侑万, 土屋聡, 谷口弘三, 戸田泰則, 日本物理学会講演概要集(CD-ROM), 79, 1, 2024

Observation of anisotropy in charge glass in θ-(BEDT-TTF)₂RbZn(SCN)₄ by Polarization-resolved ultrafast spectroscopy
和田侑万, 土屋聡, 谷口弘三, 戸田泰則, 日本物理学会講演概要集(CD-ROM), 79, 2, 2024

Frequency-sweeping optical pulse train generation using asynchronous sum frequency generation in recirculation optical system
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

Development of Spectroscopic Imaging System Based on Conversion of Polarization States for High Speed Burst Imaging
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

Generation of frequency-swept optical pulse train based on recirculation filtering of ultrafast optical pulses for sub-Gfps burst imaging
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

Spatio-temporal properties of superconductivity quenched by optical vortex pulse
尾上想一郎, 戸田泰則, 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), 70th, 2023

The origin of the resistivity increase at low temperatures in the organic Dirac electron system α-(BETS)₂I₃ probed by pump-probe spectroscopy
土屋聡, 勝見将人, 岡竜平, 内藤俊雄, 戸田泰則, 日本物理学会講演概要集(CD-ROM), 78, 2, 2023

Spatio-temporal dynamics of localized superconductivity generated by optical vortex pulse
戸田泰則, 土屋聡, 山根啓作, 森田隆二, 小田研, 黒沢徹, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 84th, 2023

有機伝導体β-(BEDT-TTF)₂I₃における光誘起金属-絶縁体相分離の探索
永田憲正, 土屋聡, 谷口弘三, 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, 57th-18th (CD-ROM), 2022

Generation of frequency-sweeping optical pulse train based on asynchronous sum frequency generation
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

Photoinduced coherent quenching of superconductivity using optical vortex pulses
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), 69th, 2022

Coherent quench spectroscopy of cuprate superconductors Bi2201
秋葉俊宏, 土屋聡, 戸田泰則, 黒澤徹, 小田研, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 69th, 2022

Photoinduced quasiparticle dynamics in Bi-based cuprates with disorder
秋葉俊宏, 土屋聡, 戸田泰則, 黒沢徹, 小田研, MERTELJ T., MIHAILOVIC D., 日本物理学会講演概要集(CD-ROM), 76, 2, 2021

Improvement in orbital angular momentum decomposition of optical vortices by using polarization gratings
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

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, 56th-17th (CD-ROM), 2021

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, 56th-17th (CD-ROM), 2021

Temperature dependence of photoinduced carrier dynamics in organic superconductor β-(BEDT-TTF)₂I₃
永田憲正, 土屋聡, 谷口弘三, 戸田泰則, 日本物理学会講演概要集(CD-ROM), 76, 1, 2021

Electronic properties of parent compounds of cuprate superconductors Nd₂CuO₄ studied by an optical pump probe spectroscopy
土屋聡, 秋葉俊宏, 中村一, 迫田將仁, 丹田聡, 戸田泰則, 日本物理学会講演概要集(CD-ROM), 75, 2, 2020

Formation of the Mott insulating state under non-equilibrium conditions in organic molecular crystal studied by three-pulse pump probe spectroscopy
土屋聡, MERTELJ Tomaz, MIHAILOVIC Dragan, 谷口弘三, 山田順一, 戸田泰則, 日本物理学会講演概要集(CD-ROM), 75, 1, 2020

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, 55th-16th, 2020

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, 55th-16th, 2020

High-precision orbital-angular-momentum decomposition system with polarization gratings
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, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 67th, 2020

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, 54th-15th, 48, 05 Jan. 2019
Japanese

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), 66th, 2019

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), 66th, 2019

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

κ-(BEDT-TTF)₂Cu[N(CN)₂]Brの超伝導状態に対するスペクトル分解ポンププローブ分光
土屋聡, MERTELJ Tomaz, MIHAILOVIC Dragan, 山田順一, 戸田泰則, 日本物理学会講演概要集(CD-ROM), 74, 1, 2019

κ型有機超伝導体のT_c以上で現れる特異的偏光応答のスペクトル分解特性
中川紘一, 佐藤貴裕, 土屋聡, 山田順一, 戸田泰則, 日本物理学会講演概要集(CD-ROM), 74, 2, 2019

時間分解分光によるκ-(BEDT-TTF)₂Cu[N(CN)₂]Iにおける不均一な電子状態の観測
土屋聡, 桑江良太, 児玉匠, 戸田泰則, 中村祐介, 栗原芽来美, 山本貴, 内藤俊雄, 日本物理学会講演概要集(CD-ROM), 74, 2, 2019

θ-(ET)₂M Zn(SCN)₄(M=Rb,Cs)における光励起キャリアダイナミクスの温度特性
中川紘一, 土屋聡, 谷口弘三, 戸田泰則, 日本物理学会講演概要集(CD-ROM), 74, 2, 2019

ピストンシリンダー型セルと光ファイバー束を用いた静水圧及び1軸性圧力下超高速時間分解分光測定装置の開発
土屋聡, 中川大輔, 戸田泰則, 高圧討論会講演要旨集, 59th, 163, 13 Nov. 2018
Japanese

Study on intensity profile correction in orbital angular momentum decomposition of optical vortices based on geometrical transformation in optics
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, ROMBUNNO.2aC5, 24 Oct. 2018
Japanese

κ‐(BEDT‐TTF)₂Cu[N(CN)₂]Clにおける光誘起キャリアダイナミクスに対する分子秩序化の影響
土屋聡, 中川紘一, 谷口弘三, 戸田泰則, 日本物理学会講演概要集(CD-ROM), 73, 2, ROMBUNNO.11aPS‐63, 21 Sep. 2018
Japanese

1軸性圧力下ポンププローブ分光測定装置の開発
土屋聡, 中川大輔, 戸田泰則, 日本物理学会講演概要集(CD-ROM), 73, 2, ROMBUNNO.11aPS‐62, 21 Sep. 2018
Japanese

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), 79th, ROMBUNNO.20a‐211A‐8, 05 Sep. 2018
Japanese

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, ROMBUNNO.20a‐211A‐7, 05 Sep. 2018
Japanese

Development of OAM sorter based on geometric transformation in optics
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, 118, 129(LQE2018 20-35), 1‐4, 05 Jul. 2018
Japanese

Coherent Spectroscopy of GaN Excitons by Using Vortex Pulses
戸田泰則, 重松恭平, 山根啓作, 森田隆二, レーザー研究, 46, 4, 210‐214, 20 Apr. 2018
Japanese

重水素化ドナーを含んだ有機超伝導体κ‐(ET)₂Cu[N(CN)₂]Brにおける光励起キャリアダイナミクスの温度特性
中川紘一, 土屋聡, 谷口弘三, 戸田泰則, 日本物理学会講演概要集(CD-ROM), 73, 1, ROMBUNNO.25aB404‐2, 23 Mar. 2018
Japanese

ピストンシリンダー型圧力セルと光ファイバー束を用いた一軸圧力下時間分解分光測定装置の開発
中川大輔, 土屋聡, 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, 53rd-14th, 41, 06 Jan. 2018
Japanese

偏光時間分解分光測定を用いたモット臨界近傍の有機超伝導体における超伝導ゆらぎの探索
中川紘一, 土屋聡, 谷口弘三, 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, 53rd-14th, 43, 06 Jan. 2018
Japanese

急冷した有機超伝導体における光励起準粒子ダイナミクス
佐藤貴裕, 土屋聡, 山田順一, 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, 53rd-14th, 42, 06 Jan. 2018
Japanese

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, 53rd-14th, 62, 06 Jan. 2018
Japanese

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, 53rd-14th, 61, 06 Jan. 2018
Japanese

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, 53rd-14th, 60, 06 Jan. 2018
Japanese

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), 65th, 2018

光波の空間モードを制御する~光渦を中心に~トポロジカル光波を用いたレーザー分光=光渦・偏光渦を用いた四光波混合分光法による物性探索=
戸田泰則, 光アライアンス, 28, 9, 11‐15, 15, 01 Sep. 2017
日本工業出版, Japanese

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), 78th, ROMBUNNO.6a‐S45‐5, 25 Aug. 2017
Japanese

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), 78th, ROMBUNNO.6p‐S45‐2, 25 Aug. 2017
Japanese

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), 78th, ROMBUNNO.6p‐S45‐4, 25 Aug. 2017
Japanese

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, 01 Mar. 2017
Japanese

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, 01 Mar. 2017
Japanese

Photoinduced Superconducting Gap and Pseudogap Dynamics in High-Tc Cuprates
戸田泰則, 黒澤徹, 小田研, 日本物理学会誌, 71, 12, 830‐835, 835, 05 Dec. 2016

We present polarization and coherent quench analyses of the gap dynamics in Bi-based high-T_c cuprates (Bi2212) using femtosecond optical pump-probe spectroscopy. The polarization analysis has addressed the rotational symmetry breakings of the dynamics, which are suppressed at room temperature and appears below T^*. The coherent quench experiment of the pseudogap has indicated an absence of long-range electronic order beyond a few coherence lengths on short timescales.

, The Physical Society of Japan, Japanese

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, 03 Mar. 2016
Japanese

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, 03 Mar. 2016
Japanese

Comment on "Higher Order Pancharatnam-Berry Phase and the Angular Momentum of Light"
Masato Suzuki, Keisaku Yamane, Kazuhiko Oka, Yasunori Toda, Ryuji Morita, 08 Feb. 2016
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., Technical report

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, 51st-12th, 35, 09 Jan. 2016
Japanese

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, 09 Jan. 2016
Japanese

有機超伝導体κ-(BEDT-TTF)₂X(X=Cu[N(CN)₂]Br,Cu(NCS)₂)における光励起準粒子緩和の温度特性
中川紘一, 土屋聡, 山田順一, 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, 51st-12th, 2016

Pb置換を行ったBi₂Sr₂CaCu₂O_8+δにおける光誘起準粒子ダイナミクス
渡邉健太, 土屋聡, 戸田泰則, 板垣征一朗, 黒澤徹, 小田研, 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, 51st-12th, 2016

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

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

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/日本光学会北海道支部合同学術講演会講演予稿集, 51st-12th, 2016

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, [Peer-reviewed]
English

Pump-probe time-resolved spectroscopy in κ-(ET)₂Cu[N(CN)₂]I
Tsuchiya Satoshi, Kodama Takumi, Nakamura Yusuke, Yamamoto Takashi, Naito Toshio, Toda Yasunori, Meeting Abstracts of the Physical Society of Japan, 71, 0, 1595, 1595, 2016
<p>有機超伝導体{\kappa}-(ET)2Cu[N(CN)2]X（X=Cl,Br,I）はアニオンの原子Xを化学置換することで、結晶構造を変化させることなく、電子物性に対する圧力効果を系統的に調査できる系として注目さている。しかし、X=Iの試料に関して作製の困難さから測定例が非常に少なく、その物性は未解明の部分が多い。今回X=Iの試料に対してフェムト秒光パルスを用いた時間分解分光行い、非平衡準粒子緩和ダイナミクスを調べた。</p>, 一般社団法人 日本物理学会, Japanese

Fluctuating Superconductivity in κ-(BEDT-TTF)₂X(X=Cu[N(CN)₂]Br，Cu(NCS)₂) Observed by Polarized Femtosecond Spectroscopy
Nakagawa Koichi, Tsuchiya Satoshi, Yamada Jun-ichi, Toda Yasunori, Meeting Abstracts of the Physical Society of Japan, 71, 0, 1596, 1596, 2016
<p>有機超伝導体!LaTeX$\kappa$-(BEDT-TTF)_2_Xではアニオン層Xに化学置換を施すことで電子相関を制御可能である。本研究では電子相関の異なるX=Cu[N(CN)_2_]Br及びCu(NCS)_2_に対しエネルギーギャップの検出が可能な偏光時間分解分光を実施した。その結果、両試料において擬ギャップ応答と考えられる空間対称性破れを検出することに成功した。さらに超伝導応答が、電子相関がより大きいX=Cu[N(CN)_2_]Brの試料では転移温度以上においても検出され、超伝導発現における電子相関の重要性を示唆する結果が得られた。</p>, 一般社団法人 日本物理学会, Japanese

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, 31 Aug. 2015
Japanese

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, 31 Aug. 2015
Japanese

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, 山根啓作, 森田隆二, 森田隆二, 戸田泰則, 戸田泰則, 日本物理学会講演概要集(CD-ROM), 70, 1, ROMBUNNO.21PCP-4, 1471, 24 Mar. 2015
The Physical Society of Japan (JPS), Japanese

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, 26 Feb. 2015
Japanese

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, 26 Feb. 2015
Japanese

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, 26 Feb. 2015
Japanese

κ-(ET)₂Cu(NCS)₂におけるポンプ-プローブ時間分解分光
土屋聡, 中川紘一, 山田順一, 戸田泰則, 日本物理学会講演概要集(CD-ROM), 70, 1, 2015

22aAS-12 Time-resolved pump-probe spectroscopy in k-(ET)_2Cu(NCS)_2
Tsuchiya S, Nakagawa K, Yamada J, Toda Y, Meeting Abstracts of the Physical Society of Japan, 70, 0, 1844, 1844, 2015
The Physical Society of Japan (JPS), Japanese

18pPSA-85 Time-resolved spectroscopy under high pressure and low temperature demonstrated with a piston-cylinder pressure cell
Tsuchiya S, Kino Y, Nakagawa K, Yamada J, Toda Y, Meeting Abstracts of the Physical Society of Japan, 70, 0, 1336, 1336, 2015
The Physical Society of Japan (JPS), Japanese

Over 1-mJ intense ultrashort optical-vortex pulse generation with programmable topological-charge control by chirped-pulse amplification
Keisaku Yamane, Keisaku Yamane, Asami Honda, Yasunori Toda, Ryuji Morita, Springer Proceedings in Physics, 162, 809, 812, 01 Jan. 2015

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, 01 Sep. 2014
Japanese

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, 01 Sep. 2014
Japanese

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, 01 Sep. 2014
Japanese

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, 01 Sep. 2014
Japanese

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, 01 Sep. 2014
Japanese

7aBB-2 Probe-polarization dependence of photo-induced quasi particle dynamics in the two-dimensional layered compound DyTe_3
Tsuchiya S, Sugawara Y, Tanda S, Toda Y, Meeting abstracts of the Physical Society of Japan, 69, 2, 554, 554, 22 Aug. 2014
The Physical Society of Japan (JPS), Japanese

STM/STSから見たBi2212の1次元変調構造とギャップサイズの相関
NONAMI TAKUYA, YOSHIDA HIROYUKI, KISHI FUMIKA, KUROSAWA TOORU, TODA YASUNORI, TAKEYAMA KOSAKU, ODA MIGAKU, IDO MASAYUKI, 日本物理学会講演概要集, 69, 2, 421, 421, 22 Aug. 2014
The Physical Society of Japan (JPS), Japanese

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, 21 Jul. 2014

30aAX-9 Study of Doppler absorption spectroscopy and multidimensional excitation using optical vortex
Aramaki M., Nonobe K., Tabei S., Toda Y., Yoshimura S., Morisaki T., Goto M., Terasaka K., Tanaka M. Y., Nishizawa N., Meeting abstracts of the Physical Society of Japan, 69, 1, 281, 281, 05 Mar. 2014
The Physical Society of Japan (JPS), Japanese

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, 03 Mar. 2014
Japanese

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, 03 Mar. 2014
Japanese

Bi₂Sr₂CaCu₂O_8+δのノード・アンチノード対称性にもとづく光誘起準粒子ダイナミクスの選択的観測
渡辺健太, 土屋聡, 戸田泰則, 板垣征一朗, 黒澤徹, 小田研, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 75th, 2014

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, 31 Aug. 2013
Japanese

Quasiparticle Dynamics of Photoexcited Superconducting Phase Transition in OD-Bi12212
Kawanokami F., Toda Y., Itagaki S., Kurosawa T., Oda M., Ido M., Meeting abstracts of the Physical Society of Japan, 68, 2, 500, 500, 26 Aug. 2013
The Physical Society of Japan (JPS), Japanese

Coherent dynamics of excitons in Wide-gap semiconductors under intense excitation conditions
Hasegawa A., Toda Y., Adachi S., Morita R., Nakayama M., Meeting abstracts of the Physical Society of Japan, 68, 2, 698, 698, 26 Aug. 2013
The Physical Society of Japan (JPS), Japanese

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, 26 Aug. 2013
The Physical Society of Japan (JPS), Japanese

29aRG-2 The discovery of chiral CDW in 1T-VSe_2
Sugawara Y., Ishioka J., Toda Y., Oda M., Kurosawa T., Matsuura T., Ichimura K., Tanda S., Meeting abstracts of the Physical Society of Japan, 68, 1, 892, 892, 26 Mar. 2013
The Physical Society of Japan (JPS), Japanese

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, 11 Mar. 2013
Japanese

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, 11 Mar. 2013
Japanese

オーバードープ高温超伝導体(Bi2212)の光誘起超伝導相転移における準粒子ダイナミクス
川之上史篤, 土屋聡, 戸田泰則, 板垣征一朗, 黒澤徹, 小田研, 伊土政幸, 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, 49th-10th, 2013

強励起条件下におけるワイドギャップ半導体励起子の縮退四光波混合
長谷川明, 戸田泰則, 足立智, 森田隆二, 中山正昭, 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, 49th-10th, 2013

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, [Peer-reviewed]
English

直鎖型Ｃ60ポリマーの電子-フォノン結合定数—光励起電子緩和レートからの算出ー
小野 頌太, 戸田 泰則, 尾上 順, ナノ学会会報, 12, 1, 11, 15, 2013
ナノ学会, Japanese

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
Japanese

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
Japanese

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, 27 Aug. 2012
Japanese

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, 27 Aug. 2012
Japanese

19aHB-11 Description of the photo-excited carrier relaxation in gapped systems by a theory of anharmonic interaction between longitudinal and transverse phonon modes
Ono Shota, Shima Hiroyuki, Toda Yasunori, Meeting abstracts of the Physical Society of Japan, 67, 2, 689, 689, 24 Aug. 2012
The Physical Society of Japan (JPS), Japanese

20pFA-2 Development of a Tunable Optical Vortex Laser for Novel Plasma Spectroscopy
Aramaki Mitsutoshi, Toda Yasunori, Yoshimura Shinji, Terasaka Kenichiro, Tanaka Masayoshi Y., Meeting abstracts of the Physical Society of Japan, 67, 2, 214, 214, 24 Aug. 2012
The Physical Society of Japan (JPS), Japanese

C-3-1 Novel multiplexed transmission based on multi-core fiber
Awaji Yoshinari, Wada Naoya, Toda Yasunori, Hayashi Tetsuya, Proceedings of the IEICE General Conference, 2012, 1, 150, 06 Mar. 2012
The Institute of Electronics, Information and Communication Engineers, Japanese

25pYH-10 Quasiparticle dynamics in photoinduced SC phase transition in UD-Bi2212
Toda Y., Mertelj T., Kusar P., Kurosawa T., Oda M., Ido M., Mihailovic D., Meeting abstracts of the Physical Society of Japan, 67, 1, 648, 648, 05 Mar. 2012
The Physical Society of Japan (JPS), Japanese

Switching by using Laguerre-Gaussian mode
AWAJI Yoshinari, WADA Naoya, TODA Yasunori, 電子情報通信学会技術研究報告. PN, フォトニックネットワーク, 111, 475, 71, 74, 05 Mar. 2012
We observed spectrum of orbital angular momentum (OAM) of Laguerre-Gaussian mode after propagation through multi-core fiber in mode-division multiplexing transmission. Main mode associated with the OAM of the input beam was observed. In addition, the satellite modes arising from the azimuthally-aligned multi-core were clearly distinguished. This means the possibility of optical path switching which can alternate any mode in OAM spectrum when individual mode is carrying communication channel., The Institute of Electronics, Information and Communication Engineers, Japanese

光渦励起による励起子軌道角運動量ダイナミクス
重松恭平, 戸田泰則, 戸田泰則, 森田隆二, 森田隆二, 日本物理学会講演概要集, 67, 1, 796, 796, 05 Mar. 2012
The Physical Society of Japan (JPS), Japanese

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, 29 Feb. 2012
Japanese

低屈折率粒子の動的自在マニピュレーションを用いた液滴融合
鹿島準一郎, 戸田泰則, 森田隆二, 応用物理学会北海道支部・日本光学会北海道地区合同学術講演会講演予稿集, 47th-8th, 2012

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, [Peer-reviewed]
English

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, 16 Aug. 2011
Japanese

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, 天野竜郎, 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-11, 16 Aug. 2011
Japanese

Preservation of orbital angular momentum of Laguerre-Gaussian passing thorough seven core fiber
AWAJI Yoshinari, WADA Naoya, TODA Yasunori, HAYASHI Tetsuya, IEICE technical report, 111, 69, 25, 28, 19 May 2011
It has been observed that orbital angular momentum spectra of Laguerre-Gaussian mode was preserved after passing through several core of image fiber. In this report, we advanced this scheme by using seven core fiber which had less (coarse) number of cores (pixels) and verify it experimentally., The Institute of Electronics, Information and Communication Engineers, Japanese

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
鈴木雅人, 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), 58th, 2011

20aHX-2 Measurement of chirality of CDWs in TiSe_2 by using STM and optical ellipsometry
Ishioka J, Shimatake K, Kurosawa T, ichimura K, Toda Y, Oda M, Tanda S, Meeting abstracts of the Physical Society of Japan, 65, 1, 812, 812, 01 Mar. 2010
The Physical Society of Japan (JPS), Japanese

光ファイバー中での光渦の発生と精密制御
斎藤崇広, 戸田泰則, 森田隆二, Optics & Photonics Japan講演予稿集, 2010, 2010

偏光分散のない超広帯域偏光渦パルス発生
時実悠, 岡和彦, 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), 57th, 2010

コヒーレント複合光渦パルスの生成と制御
本田翔一, 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), 57th, 2010

バンドルファイバーによるコヒーレント複合光渦パルスの伝送
本田翔一, 戸田泰則, 淡路祥成, 上野雄鋭, 森田隆二, 応用物理学会学術講演会講演予稿集(CD-ROM), 71st, 2010

Photo-induced Carrier Dynamics in a Quasi-one-dimensional Material with Curved Morphology
TODA Yasunori, Journal of the Surface Science Society of Japan, 30, 12, 667, 672, 10 Dec. 2009
日本表面科学会, Japanese

偏光渦パルス励起によるリング結晶の閉ループ特性の評価
時実悠, 島竹克大, 戸田泰則, 岡和彦, 丹田聡, 森田隆二, 応用物理学関係連合講演会講演予稿集, 56th, 3, 2009

四光波混合を用いた光の軌道角運動量の変換
上野雄鋭, 戸田泰則, 足立智, 森田隆二, 俵毅彦, 応用物理学会学術講演会講演予稿集, 70th, 3, 2009

非線形媒質中における光渦対の伝播ダイナミクス
本田翔一, 上野雄鋭, 森田隆二, 戸田泰則, 応用物理学会学術講演会講演予稿集, 70th, 3, 2009

Photoinduced electron dynamics in low-dimensional topological materials
SHIMATAKE Katsuhiro, TODA Yasunori, 應用物理, 77, 6, 672, 675, 10 Jun. 2008
応用物理学会, Japanese

擬一次元導体TaS₃におけるコヒーレント電子集団励起の観測
小野崎龍恒, 小野崎龍恒, 坪田雅功, 丹田聡, 戸田泰則, 応用物理学関係連合講演会講演予稿集, 55th, 3, 1139, 27 Mar. 2008
Japanese

26aRH-3 Observation on Coexisting SC and PG Quasiparticles in Bi2212 by Time-Resolved Optical Spectroscopy
Liu Y.H., Toda Y., Shimatake K., Momono N., Oda M., Ido M., Meeting abstracts of the Physical Society of Japan, 63, 1, 630, 630, 29 Feb. 2008
The Physical Society of Japan (JPS), English

四光波混合分光によるGaN励起子のトポロジカル解析
上野雄鋭, 上野雄鋭, 戸田泰則, 戸田泰則, 足立智, 森田隆二, 俵毅彦, 応用物理学会学術講演会講演予稿集, 69th, 3, 2008

21pXQ-13 Ultrafast Time-resolved Optical Spectroscopy of Charge-Density-Wave Phase Transition Dynamics in NbSe_3
Shimatake K., Onozaki T., Toda Y., Tanda S., Meeting abstracts of the Physical Society of Japan, 62, 2, 810, 810, 21 Aug. 2007
The Physical Society of Japan (JPS), Japanese

擬一次元TaS₃の光励起ダイナミクスにおける共鳴効果
小野崎龍之, 坪田雅功, 丹田聡, 戸田泰則, 日本物理学会講演概要集, 62, 2, 782, 782, 21 Aug. 2007
The Physical Society of Japan (JPS), Japanese

Optical spectroscopy for topological characterization of materials
戸田 泰則, 島竹 克大, Materials integration, 20, 5, 44, 48, May 2007
ティー・アイ・シィー, Japanese

23pZA-4 Systematic study of coherent collective excitations observed in transient reflectivity changes
Toda Y., Shimatake K., Onozaki T., Tanda S., Meeting abstracts of the Physical Society of Japan, 61, 2, 637, 637, 18 Aug. 2006
The Physical Society of Japan (JPS), Japanese

24aWB-6 Time-frequency property of coherent oscillations in quasi-one-dimensional charge-density-wave compound TaS_3
Onozaki T., Shimatake K., Tanda S., Toda Y., Meeting abstracts of the Physical Society of Japan, 61, 2, 584, 584, 18 Aug. 2006
The Physical Society of Japan (JPS), Japanese

27pXF-8 Femto-second Dynamics in Quasi-One-Dimensional Conductor of NbSe_3 by means of Two-color Excitations
Shimatake K., Toda Y., Tanda S., Meeting abstracts of the Physical Society of Japan, 61, 1, 772, 772, 04 Mar. 2006
The Physical Society of Japan (JPS), Japanese

25pXL-6μ-time-resolved spectroscopy of quasi-one-dimensional compound NbSe_3
Shimatake K., Toda Y., Tanda S., Meeting abstracts of the Physical Society of Japan, 60, 1, 742, 742, 04 Mar. 2005
The Physical Society of Japan (JPS), Japanese

24aPS-42 Four wave mixing spectroscopy of GaN films on A-plane sapphire
Toda Y., Adachi S., Abe Y., Hoshino K., Arakawa Y., Meeting abstracts of the Physical Society of Japan, 60, 1, 667, 667, 04 Mar. 2005
The Physical Society of Japan (JPS), Japanese

12pTM-4 Time-Resolved Micro-Optical Spectroscopy for the Quasi-One-Dimensional Conductor of NbSe_3
Shimatake K., Minami T., Toda Y., Tanda S., Meeting abstracts of the Physical Society of Japan, 59, 2, 699, 699, 25 Aug. 2004
The Physical Society of Japan (JPS), Japanese

低次元導体における電荷密度波テラヘルツ振動のコヒーレント制御
戸田泰則, 森田隆二, 丹田聡, 応用物理学会学術講演会講演予稿集, 65th, 3, 2004

Collective excitations and their temperature dependences of CDW in 1T-TaS_2
Toda Y, Tateishi K, Inagaki K, Ichimura K, Tanda S, Meeting abstracts of the Physical Society of Japan, 58, 2, 646, 646, 15 Aug. 2003
The Physical Society of Japan (JPS), Japanese

2パルス励起による有機分子の選択的コヒーレント振動状態制御
伊藤晃一, 立石幸一, 森田隆二, 山下幹雄, 戸田泰則, 応用物理学関係連合講演会講演予稿集, 50th, 3, 2003

近赤外励起におけるバルクGaNの多光子吸収過程の観測
松原崇史, 戸田泰則, 森田隆二, 山下幹雄, 星野勝之, 染谷隆夫, 荒川泰彦, 応用物理学関係連合講演会講演予稿集, 50th, 1, 2003

Scanning near-field optical spectroscopy for semiconductor quantum nano-structures
TODA Yasunori, ARAKAWA Yasuhiko, 應用物理, 71, 6, 714, 715, 10 Jun. 2002
Japanese

バルクGaNの時間分解ポンプ・プローブ分光
松原崇史, 戸田泰則, 森田隆二, 山下幹雄, 星野勝之, 染谷隆夫, 荒川泰彦, 応用物理学会学術講演会講演予稿集, 63rd, 1, 2002

銀コロイド溶液のフェムト秒ダイナミクス
伊藤晃一, 立石幸一, 森田隆二, 山下幹雄, 戸田泰則, 応用物理学会学術講演会講演予稿集, 63rd, 3, 2002

Magneto-optical spectroscopy of single self-assembled quantum dots
TODA Y., ARAKAWA Y., Meeting abstracts of the Physical Society of Japan, 53, 2, 231, 231, 05 Sep. 1998
The Physical Society of Japan (JPS), Japanese

Laser Spectroscopy Using Topological Light Beams　　　　　　　　　　　　　　　
Yasunori Toda
Springer Series in Progress in Nanophotonics 3, 2014, [Joint work]

光物性入門　　　　　　　　　　　　　　　
戸田泰則
朝倉書店, 2009, [Joint work]

ナノオプティクス：ナノスケールの光物性　　　　　　　　　　　　　　　
戸田泰則
オーム社, 2004, [Joint work]

Optical Characterization of In(Ga)As/GaAs Self-assembled Quantum Dots Using Near-Field Spectroscopy　　　　　　　　　　　　　　　
Yasunori Toda
Springer Series in Optical Sciences Volume 86, 2003, [Joint work]

ナノ光工学ハンドブック　　　　　　　　　　　　　　　
戸田泰則
朝倉書店, 2002, [Joint work]

Ultrafast beam pattern modulation with spiral symmetry by spatiotemporal coupling of ultrafast optical vortex pulses and its application
Grants-in-Aid for Scientific Research
01 Apr. 2023 - 31 Mar. 2026
森田 隆二, 戸田 泰則
本研究の目的は，光の持つ位相・偏光の空間的特異性・非一様性に着目し，申請者らが現在までに独自に開発したモノサイクル域光パルス発生・制御技術，さらには光波時空間結合コヒーレント合成技術を用いることにより，以下のことを行うことである。すなわち，時間的にチャープした光渦パルス等のコヒーレントビーム合成による，らせん形状・円筒対称ビームパターンTHz変調手法の確立，この技術を発展させ，様々ならせん形状・円筒対称を持つTHz変調動的光モードの生成，さらに生成ビームによる物質系における擬粒子励起とそのコヒーレント伝播制御・増強・対称性を有した新奇現象探索を行うことである。


既に申請者らは，THz回転周波数の超高速回転光格子（光渦ペア）発生に成功しているが，これは方位角依存の位相の干渉効果によるものである。物質系における擬粒子励起などの応用を考え，当該年度はさらなる自由度として動径座標依存の位相変調の導入を行った。「方位方向依存位相+動径方向依存位相」の干渉効果を用いると，「らせん方向」ビーム変調が可能となり，これを超高速で回転させることができる。


具体的には，動径方向依存+方位方向依存位相変調の自在性を与えるため，プログラマブル空間位相変調器を用いており，その光損傷閾値を超えない程度の光源の増幅を行っている。また，光渦の重ね合わせ光学系としては，光損失が少なく安定でロバストなコヒーレントビーム合成光学系を，Sagnac型干渉計光路を用いて構築している。
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 23K26566

特異点光波による光誘起ナノスケール超伝導の創製
科学研究費助成事業
01 Apr. 2022 - 31 Mar. 2025
戸田 泰則, 小田 研, 土屋 聡
本研究では特異点光波（光渦パルス）を物質の電子状態に対して空間的に高速制御する手段として活用し、超伝導体試料に対して光誘起のナノスケール超伝導を創出する。現在までに１）光誘起相転移を観測する分光手法（コヒーレントクエンチ分光）への特異点光波の適用、２）特異点周りの強度暗点に形成される局在超伝導の応答検出、および３）局在超伝導を用いた超伝導試料に対する空間イメージングを実現した。特異点光波のフルーエンス変化にもとづく超伝導応答の空間分布先鋭化が確認され、超伝導の非熱的相破壊（クエンチ）を反映する飽和特性を利用した超解像化を実証することができた。特に局在化超伝導サイズの適切な見積もりと物性解析に対する有効性を示すため、空間分解イメージングを用いて超伝導応答の時空間変化を系統的に調査した。具体的には強度暗点に形成される超伝導サイズの相破壊パルス強度に対する依存性、クエンチ後の経過時間に対する依存性を観測し、結果から、１）強度暗点に形成される局在超伝導のサイズが約100nmに到達すること、２）局在超伝導の存在時間はクエンチされた領域の超伝導回復時間（＜10ps）で決定されることを明らかにした。バルクの性質をもつ超伝導状態をナノスケールで観測・制御する手法は画期的であり、実際に超伝導応答の時空間分布を示すことで本手法が超伝導物性探索の強力なツールとなりうることを示すことができた。合わせて新機能開拓に対する本手法の有効性を示すため、高温超伝導体に特徴的に現れる擬ギャップと呼ばれる電子状態に対しても同様の光誘起局在化の実証実験に取り組んだ。プロセスフリーで電子状態の時空間制御を可能とする本手法の特徴を生かし、超伝導体特有の電子状態に対して非熱的空間変調にもとづく機能応用の道筋を開拓できた。
日本学術振興会, 基盤研究(B), 北海道大学, 23K23246

３パルス型フェムト秒時間分解分光による電荷ガラス転移における動的不均一性の探索
科学研究費助成事業
01 Apr. 2022 - 31 Mar. 2025
土屋 聡, 戸田 泰則, 谷口 弘三
本研究の最終目標である「ガラス転移の解明」に向けて、近年基礎、応用の両面から注目を集めている有機分子結晶の電荷ガラス状態を研究対象とし、フェムト秒光パルスを用いた電子の緩和ダイナミクス測定を実施し、ガラス転移に対する新たな知見を得ることを目的とする。
２年目は初年度に得たガラス状態を特徴付ける緩和ダイナミクスの普遍性を調査した。まず初年度に測定したtheta-(BEDT-TTF)2RbZn(SCN)4、theta-(BEDT-TTF)2CsZn(SCN)4、ZnをCoに置換したtheta-(BEDT-TTF)2RbCo(SCN)4、theta-(BEDT-TTF)2CsCo(SCN)4に注目した。これらCo塩の基礎物性はRb塩と非常によく似ていることがわかっており、Rb塩と同様の電荷秩序、電荷ガラスを特徴付ける光誘起キャリアダイナミクスが観測されることが期待される。Co塩において２パルス型ポンププローブ分光測定を実施したところ、Rb塩とどうようの傾向のダイナミクスが観測され、普遍性があることが確認できた。
また電荷秩序を特徴付けるダイナミクスが他の物質でも観測されるか探るため、alpha-(BEDT-TTF)2I3、alpha-(BETS)2I3においても測定を行った。これまでの研究からalpha-(BEDT-TTF)2I3では低温で電荷秩序に相転移し、alpha-(BETS)2I3は電荷秩序ではない絶縁体に転移することがわかっているため、これら２物質での結果を比較することで、電荷秩序を特徴付けるダイナミクスの普遍性についての知見が得られると考えた。測定の結果、電荷秩序を示すalpha-(BEDT-TTF)2I3ではtheta塩の電荷秩序と同様のダイナミクスが観測され、alpha-(BETS)2I3では、電荷秩序とは異なるダイナミクスが観測された。このことから電荷秩序ダイナミクスの普遍性を確認することができた。この成果の一部は論文として出版した。
日本学術振興会, 基盤研究(B), 北海道大学, 23K22433

３パルス型フェムト秒時間分解分光による電荷ガラス転移における動的不均一性の探索
科学研究費助成事業
01 Apr. 2022 - 31 Mar. 2025
土屋 聡, 戸田 泰則, 谷口 弘三
日本学術振興会, 基盤研究(B), 北海道大学, 22H01162

特異点光波による光誘起ナノスケール超伝導の創製
科学研究費助成事業
01 Apr. 2022 - 31 Mar. 2025
戸田 泰則, 小田 研, 土屋 聡
日本学術振興会, 基盤研究(B), 北海道大学, 22H01978

量子液晶の制御と機能
科学研究費助成事業 新学術領域研究(研究領域提案型)
28 Jun. 2019 - 31 Mar. 2024
小林 研介, 戸田 泰則, 戸川 欣彦, 石坂 香子, 岡崎 浩三, 有馬 孝尚
小林は、量子ドットにおける近藤効果を用いて、平衡非線形領域にある微分伝導度について調べ、平衡から遠く離れた状況にあったとしても、対称性を通じて近藤効果が輸送現象に姿を表すことを微視的に実証した。さらに、GaAs/AlGaAsトンネル結合二重量子井戸構造におけるラシュバ効果、スピン軌道トルクによる磁化の準安定状態の実現や、電流雑音測定のための低温増幅器の開発などを行った。有馬は、希土類を含むいくつかの合金系について共鳴Ｘ線散乱や中性子散乱を行い、磁場や温度およびそれらの履歴によって多彩な磁気ナノ超構造の間を転移する様子を逆空間で観測することでスピン液晶状態を確定させるという成果を得た。戸川はキラルスピン物質CrNb3S6が示す異方的磁気共鳴の研究を行い、励起配置に強く依存した共鳴応答を見出し、共鳴スイッチングやキラルソリトン共鳴モードの切替えなど、高度な制御法に関する成果を得た。戸田はトポロジカル光波を用いた光誘起相制御開拓の研究を行い、光の伝播がもたらす幾何学位相（グイ位相）の制御性を活用した光渦発振を半導体微小共振器に対して実現した。石坂は遷移金属ダイカルコゲナイドVTe2を対象とし、数ピコ秒の時間分解能による電子回折とイメージング実験を行い、電荷密度波の超高速融解とそれに伴う特異な偏極を持つ音響フォノンの生成・伝播の計測に成功した。岡﨑は、高次高調波レーザーを用いた時間分解光電子分光による光照射による物性制御の研究を行い、鉄系超伝導体FeSeにおいて、光誘起超伝導による超伝導ギャップの観測に成功する、という成果を得た。
日本学術振興会, 新学術領域研究(研究領域提案型), 19H05826

Ultrafast beam pattern modulation using the superposition of chirped ultrashort optical vortex pulses and its application
Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
01 Apr. 2020 - 31 Mar. 2023
森田 隆二, 戸田 泰則
本研究の目的は，光の持つ位相・偏光の空間的特異性・非一様性に着目し，申請者らが現在までに独自に開発したモノサイクル域光パルス発生・制御技術，超短光パルスコヒーレント合成技術，光のスピン軌道相互作用変換・制御技術を用いることにより， THzの速さでビームパターンが変化する光格子（光渦ペア）を発生させること，さらに，物質系において，発生光渦ペアによる擬粒子励起を行い，その伝播過程を利用してコヒーレントな制御・増強を行うことである。既に申請者らは，THz回転周波数の超高速回転光格子（光渦ペア）発生に成功しているが，物質系における擬粒子励起などの応用を考えると，十分な光出力とはいえない。そこで，まず，THz回転周波数の超高速回転リング状光格子（光渦ペア）の高強度化をめざし，当該年度は以下を行った。


光源系の改良としては，光損失が少なく安定でロバストなコヒーレントビーム合成光学系としてサニャック型干渉計光路を用い，変調前のパルスエネルギー360 μJ，変調後のパルスエネルギー115 μJ，32%の高い変換効率を得ている。また，チャープされた光渦の重ね合わせ実験において，絶対値が等しく符号の異なるトポロジカルチャージを有する光渦パルスの重ね合わせ手法を拡張し，方位方向指数の異なる光渦の重ね合わせによる動径方向に変化する高効率超高速ビーム変調，方位方向指数および動径方向指数の異なる光渦の重ね合わせによる複雑な超高速ビームパターン変調に成功している。
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 20H02645

Application of optical vortex spectroscopy to process plasma and development to new material creation
Grants-in-Aid for Scientific Research Fund for the Promotion of Joint International Research (Fostering Joint International Research (B))
09 Oct. 2018 - 31 Mar. 2023
荒巻 光利, 吉村 信次, 寺坂 健一郎, 矢澤 翔大, 小林 弘和, 戸田 泰則, 鹿野 豊
本研究の目的は，光渦分光法をプロセスプラズマに適用することでプラズマの制御性を格段に向上させ，そのプラズマ源を材料開発に応用することである．2019年度は，2020年度以降のドイツおよびデンマークでの実験に備えた装置開発および予備実験を行った．
ドイツ・ルール大学との共同研究では，容量結合プラズマ（CCP）と基板の境界であるシース内における，イオン流速の測定を目的としている．CCPは広くプラズマプロセスで用いられており，シース内で基板に垂直方向に加速されたイオンのエネルギーは，膜質を左右する重要なパラメータである．従来は，基板に穴をあけてレーザーを基板に垂直方向にレーザーを通すか，イオンを引き出してエネルギーアナライザで検出するなどし基板への入射エネルギーが測定されてきた．本研究では，基板に平行な方向から入射した光渦によって，基板に垂直な方向のイオン流速を測定することを目指している．従って，基板や電極を加工する必要がなく，実機への応用も可能となる．2019年度は，光渦を用いたレーザー誘起蛍光測定系を開発し，HYPER-II（九州大学）での予備実験を開始した．
デンマーク工科大学との共同研究では，希少金属を用いない透明電極の高性能化に関する研究を進めている．現時点で得られている導電性透明薄膜は，電気特性の位置依存性が大きく，何が特性を決めているのか明らかになっていない．本共同研究では，光渦分光により，基板直前のイオン・原子のエネルギー分布を測定し，薄膜の電気的特性との関係を明らかにすることを目指している．2019年度は，予備的実験として，デンマーク工科大学にて，DCスパッタリングプラズマの発光分光測定を開始し，観測可能なAr, Zn, Aｌ等の発光線を検討した．
Japan Society for the Promotion of Science, Fund for the Promotion of Joint International Research (Fostering Joint International Research (B)), Nihon University, 18KK0079

光渦の空間モードカイラリティを活用した時間分解分光の開発
科学研究費助成事業 挑戦的研究(萌芽)
28 Jun. 2019 - 31 Mar. 2022
戸田 泰則
光渦は高次の空間モード光波に対応し、その特徴である波面の回転位相勾配は勾配の方向（符号）に応じたカイラリティを持つ。したがって異なるカイラリティを持つ同一次数の光渦対を用いると、完全同軸の光励起に対してカイラリティ選択による渦対の分離が可能となる。本研究ではこの光渦カイラリティに着目し、モード変換を利用した光波分離にもとづく全く新しい方式の時間分解分光を開発することを目的としている。
提案手法を確立するため、昨年度は主にカイラリティの異なる光渦の生成分離に対する光学系の確立と最適化に取り組んだ。解決課題として、（i）光渦の空間モード純度、（ii）検出側の空間モード選択性、（iii）試料反射特性、を設定し、
（項目A）半導体面発光レーザー（VCSEL）に対する空間モード選択制御
（項目B）高温超伝導体試料（Bi2212）の完全同軸型ポンププローブ分光
を実施した。項目Aでは光波の空間モード純度（課題i）と選択性（課題ii）の向上を図り、光注入型VCSELにおけるカイラリティ選択可能な光渦発振を実現した。特に共振器の幾何学位相（グイ位相）にもとづく空間モード変換を用いることにより、非対称共振器に対しても光渦発振可能であることを明らかにし、汎用性の高い光渦レーザー実現に向けた原理実証を行った。並行して項目Bでは空間モードカイラリティを活用した時間分解分光開発に取り組み、直交偏光条件下の完全同軸型時間分解ポンププローブ分光によるカイラリティ選択型過渡応答検出を実現した（課題ii）。
日本学術振興会, 挑戦的研究(萌芽), 北海道大学, 19K22138

Spatio-temporal control of superconducting phase by optical vortex pulses
Grants-in-Aid for Scientific Research
01 Apr. 2019 - 31 Mar. 2022
TODA YASUNORI
Excitation of all superconducting (SC) Cooper pairs with ultrashort laser pulses induces a coherent quench to the normal state in the photoexcited region. In this study, we have performed coherent quenching of high-Tc SCs using optical vortex pulses with unique spatial characteristics in the beam cross-section. Our newly developed time-resolved spectroscopy demonstrated the generation as well as the observation and control of a novel SC state modulated in space and time. This achievement demonstrates a new type of photo-induced phase transition utilizing the spatial controllability of light waves, showing promise for applications in nano-scale imaging and the development of SC devices.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 19H02621

実空間と時間の両領域で見る銅酸化物における擬ギャップ状態と高温超伝導の関わり
科学研究費助成事業 基盤研究(C)
01 Apr. 2019 - 31 Mar. 2022
小田 研, 戸田 泰則
本研究では、代表的な銅酸化物高温超伝導体の一つであるBi2212で走査トンネル顕微鏡分光（STM/STS）とポンプ・プローブ時間分解分光（PPTS）を行い、実空間と時間空間の双方から「高温超伝導体に固有の擬ギャップ（PG）現象を担う電子系と高温超伝導の発現との関係性」の解明にアプローチする。２０１９年度は不足キャリア（ホール）濃度のBi2212単結晶試料でSTM/STS実験とPPTS実験を行い、以下に記す成果を得た。
１．STM/STSでは、PGにかかる電子系のチェッカーボード様変調構造が超伝導にかかる準粒子の干渉による変調構造と実空間の同じ領域において共存することが明らかとなった。また、両者の共存関係を相互相関関数の手法により調べた結果、明確な実空間相関が観測され、チェッカーボード様変調構造の起源やPG状態と超伝導に関係する電子状態間の相互作用の可能性を明らかにする上で有用な知見が得られた。
２．PPTSでは、高強度ポンプパルス光の照射によりPG状態と超伝導相を局所的に破壊し、その後の両者の回復過程をプローブ光の反射応答を通して調べた。その結果、PG状態がほぼ回復した後に超伝導状態の形成が始まること、すなわち、両者の間に明確な時間相関のあることが分かった。これはPG状態が高温超伝導の発現に本質的に関わっていることの一つの証拠に成り得ると考えられる。
２０２０年度以降の研究では、最適ホール濃度および過剰ホール濃度領域のBi2212試料にも研究を広げ、これらの試料で得られた結果も含めて総合的に考察し、PGを担う電子状態と超伝導の発現との関わりについて明らかにする。
日本学術振興会, 基盤研究(C), 北海道大学, 19K03732

Global quantum correlation dynamics investigations using optical orbital angular momentum
Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
01 Apr. 2016 - 31 Mar. 2019
TODA YASUNORI
Using ultrafast optical vortex pulses, we have demonstrated the observation of the orbital angular momentum (OAM) dynamics of carriers for high-Tc superconductors (Bi2212) and obtained the following results: (a) OAM-dependent transient reflectivity changes are observed below Tc, indicating that the optical vortex can transfer its OAM to the superconducting state (quasi-particles and/or cooper-pairs); (b) recovery dynamics of the superconducting state shows an efficient contribution of the pairing fluctuation in its early stage; (c) temperature dependence of the OAM dynamics shows virtually no pairing fluctuation, suggesting that the optical vortex induced OAM dynamics reflects a spatially coherent dynamics associated with a global quantum correlation.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 16H03876

光の軌道角運動量を用いた巨視的量子相関ダイナミクス探索　　　　　　　　　　　　　　　
基盤研究(B)
2016 - 2018
戸田泰則
日本学術振興会, Principal investigator, Competitive research funding

Time-resolved coherent polarimetry using polarization vortices
Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research
01 Apr. 2015 - 31 Mar. 2017
Toda Yasunori
We have developed a novel type of coherent spectroscopy (time-resolved polarimetry using nonlinear laser spectroscopy known as degenerate four-wave-mixing) using polarization vortices characterized by a vector singularity on the beam cross-section, and performed the spectroscopy on semiconductor GaN excitons (electron-hole pairs). We successfully obtained the results concerned as follows: (a) quantitative snap-shot evaluations of exciton spin exchange and uniaxial strain energies; especially for small residual anisotropies in isotropic samples; (b) coherent dynamics of the polarization singularities resulting from broken rotational symmetries of excitons, (c) spin and pseudo-spin dynamics and their correlations resulting from excitons interactions.
Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Exploratory Research, Hokkaido University, 15K13369

Generation of intense topological light waves in the mono-cycle regime by coherent beam combining and their application
Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
01 Apr. 2014 - 31 Mar. 2017
MORITA Ryuji
Over 1 mJ pulse intense optical vortex pulses (duration of 27 fs) were generated with programmable topological-charge control. Ultra-broadband polarization vortex pulses (wavelength range of 750 to 880 nm) were successfully synthesized from two orthogonally polarized optical vortex pulses by using coherent beam combining. Moreover, the extended Stokes parameters were newly introduced, enabling one to precisely evaluate polarization symmetry and spatial polarization purity for ultra-broadband polarization vortex pulses. Furthermore, snap-shot polarization spectroscopy through four-wave mixing signals from GaN by use of radially polarized ultrashort pulses was performed, giving high sensitivity and high precision.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 26286056

Study on photoexcitation, novel plasma spectroscopy, and plasma control method using optical vortex
Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
01 Apr. 2013 - 31 Mar. 2017
ARAMAKI Mitsutoshi, ITO Kiyokazu
Optical vortex (OV) beams are a set of solutions of the paraxial Helmholtz equation in the cylindrical coordinates, and its wave front has a spiral shape. The observer in the OV beam feels the three-dimensional Doppler effect, since the OV beam has the three-dimensional spiral wave front. In this study, spectroscopy methods which have the sensitivity to the beam crossing gas flow have been developed. Using the optical vortex spectroscopy methods, the beam-crossing gas flow was successfully detected as the transverse Doppler shift of the Doppler absorption spectrum and the Lamb dip shift of the saturated absorption spectrum, respectively. The dependence of the transverse Doppler shift on the distance from the phase singularity qualitatively agrees with the theory, however, the further improvement in accuracy of the transverse Doppler shift detection is required for the quantitative evaluation.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), 25287152

偏光渦パルスを用いた時間分解コヒーレントポラリメトリ　　　　　　　　　　　　　　　
挑戦的萌芽研究
2015 - 2016
戸田泰則
日本学術振興会, Principal investigator, Competitive research funding

Multi-dimensional degenerate four-wave-mixing spectroscopy using topological transformation
Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research
01 Apr. 2013 - 31 Mar. 2015
TODA YASUNORI, ADACHI Satoru, NAKAYAMA Masaaki
Spatiotemporal four-wave mixing (FWM) spectroscopy of semiconductor excitons was developed by using (A) variably controlled Laguerre-Gaussian (LG) pulses, (B) orbital angular momentum (OAM) resolved spectroscopy with high precision. The observed exciton OAM dynamics indicates that (1) near perfect OAM transfer to the exciton center-of-mass motion is achieved using the LG pulses with nonzero OAM, (2) imperfect conversion becomes significant when the excitation pulses include an OAM-free component (3) an extremely long OAM decay was observed in the bulk sample, which implies a small spatial variation of the exciton dephasing. Moreover, the topological charge dependence of the OAM dynamics suggests a robustness of the exciton OAM. For the application of the topological transformation, a novel spatially modulated optical feedback in a vertical-cavity surface-emitting laser was demonstrated for the first time, where the results show high selectivity of the OAM in the transverse mode.
Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Exploratory Research, Hokkaido University, 25600105

Photoinduced superconducting phase transition dynamics in Bi-based high-Tc superconductors
Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
01 Apr. 2012 - 31 Mar. 2015
TODA YASUNORI, ODA Migaku
Photoinduced phase transition dynamics in the superconducting and pseudogap states of Bi-based high-Tc superconductors have been investigated using ultrashort pulses and the following conclusions are obtained: 1) existence of a spontaneous symmetry breaking in the psuedogap state, 2) distinct relationship between phase coherence and gap formation, 3) absence of long-range electronic ordering and carrier lorcalization in the pseudogap formation, 4) enhanced contribution of the pseudogap to the gap formation in the underdoped sample.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 24340063

Control of spin-orbit interaction of optical pulses in the mono-cycle regime and its application
Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
01 Apr. 2011 - 31 Mar. 2014
MORITA Ryuji, TODA Yasunori
Few-cycle optical-vortex pulse generation and over-mJ intense, 27 fs optical-vortex pulse generation with programmable topological-charge control were first performed. Furthermore, the measurement of the orbital-angular-momentum spectra of ultra-broadband optical-vortex pulses with high precision was demonstrated in quasi-real time. The time-resolved nonlinear spectroscopy technique using optical vortices as a pump and a probe was developed, enabling us to evaluate the relaxation time of orbital angular momentum of the GaN exciton. In addition, chiral nanostructures of metal were first fabricated by using spin- and orbital-angular momentum controlled optical-vortex pulses.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 23360024

トポロジカル変換を用いた縮退四光波混合分光の多次元化　　　　　　　　　　　　　　　
挑戦的萌芽研究
2013 - 2014
戸田泰則
日本学術振興会, Principal investigator, Competitive research funding

ビスマス系高温超伝導体における光誘起超伝導相転移ダイナミクスの研究　　　　　　　　　　　　　　　
基盤研究(B)
2012 - 2014
戸田泰則
日本学術振興会, Principal investigator, Competitive research funding

STM studies on magnetic field induced electronic charge order
Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
2010 - 2012
ODA Migaku
In this research project, we performed STM/STS experiments under magnetic fields and pump-probe optical experiments in one of the typical high-Tc cuprates Bi2212 to clarify the origin of the electronic charge order accompanied by a pseudogap and its relation to the high-Tc superconductivity. STM/STS experiments suggested that the electronic charge order will be understood in terms of the charge-spin stripes model, and dynamically fluctuating in nature. In pump-probe optical experiments, furthermore, it was found that the electronic charge order and pseudogap do not only compete with but also is needed for the high-Tc superconductivity. Employing these results, we pointed out that the fluctuating stripes would be responsible for the formation of high-Tc superconductivity.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 22540357

時空間制御光波を用いた電子相関物質における巨視的量子コヒーレンスの探索研究　　　　　　　　　　　　　　　
優秀若手研究者海外派遣事業
Mar. 2010 - Jan. 2011
戸田泰則
日本学術振興会, Principal investigator, Competitive research funding

Development of new science on electronic systems in curved spaces
Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research on Innovative Areas (Research a proposed research project)
2009 - 2011
ONOE Jun, SHIMA Hiroyuki, TODA Yasunori
A. Einstein first applied Riemannian geometry to develop the general theory of relativity almost one hundred years ago (1916) and succeeded in understanding astronomical-scale phenomena such as the straining of time-space by a gravitational field (1920). Whether or not Riemannian space affects the electronic properties of condensed matters on a much smaller scale is of great interest. Although Riemannian geometry has been applied to quantum mechanics since the 1950s, nobody has yet answered this question, because the electronic properties of materials with Riemannian geometry have not been examined experimentally. By examining in situ high-resolution ultraviolet photoemission spectra of a one-dimensional metallic C_<60> polymer with an uneven periodic peanut-shaped structure, we first observed Riemannian geometrical effects on the electronic properties of materials such as Tomononaga-Luttinger liquids, which were previously theoretically predicted by our group.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research on Innovative Areas (Research a proposed research project), Tokyo Institute of Technology, 21200032

Development of a single molecular switch by controlling phase and amplitude of optical electric fields in extremely short time region
Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
2008 - 2010
MORITA Ryuji, TODA Yasunori
Azobenzene single molecules before and after photo-isomerization were observed by a scanning tunneling microscopy. On the metal substrate with strong adsorption interaction, in-plane trans-azobenzene molecules were found, implying the inversion mechanism is dominant. Furthermore, for controlling photo-isomerization or molecular conformation change, optical pulses with spatially-dependent phase and polarization were generated with high efficiency. In addition, using the pulses, nonlinear spectroscopy along a ring shape was established. Metal surface ablation experiments were performed, demonstrating total angular momentum effects.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 20360025

Electron spin transfer of single quantum dots by using teraheltz and/or laser lights
Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
2005 - 2007
ADACHI Satoru, TODA Yasunori, MUTO Shunichi
In this project, we aimed the development of the technique to transfer the spin between the Zeeman-split electron states in a single quantum dot (QD). Then, we tried the following two methods; use of teraheltz wave and two-photon process via half-localized state in a QD. As a consequence, by the latter method, we succeeded the control of the exciton spin state and the details were published in the academic journals. In the experiments, depending on the light polarizations of the co-linearly propagating delay-controlled double pulses, we observed the in-phase and out-of-phase oscillations of photoluminescence (PL) from the Zeeman-split two exciton states. In the case of the out-of-phase oscillations, the oscillation of the Zeeman splitting energy as well as the magnitude of the PLs was observed. This is because the nuclear spin polarization in a QD was formed and followed the modulation of the electron spin polarization. This result indicates that the half-localized state of QDs is available as the intermediate state in the Lambda-type transition in order to control of the electron and nuclear spins. In addition, we investigated the hyperfine interaction between electron and nuclear spins in a single QD, and the bistability and hysteretic response of the nuclear spin polarization were observed in the dependence on excitation power, polarization, and external magnetic field. By using this nuclear spin switching, we proved that the effective g factor of the QD electron could be tuned widely from negative to positive and be set to zero.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 17310056

トポロジカル物性解析のための非線形分光計測手法の開発
科学研究費助成事業 萌芽研究
2006 - 2006
戸田 泰則
本研究では、結晶のトポロジカルな空間対称性の破れに起因する電子状態の空間位相変化を検出する手法の確立を目的とした。本年度の成果として、1)四光波混合(FWM)分光を用いた位相干渉計測の確立、2)結晶トポロジーを反映した電子状態の時間特性変化の観測、3)トポロジー光パルスの発生と解析評価の確立、を達成した。FWMをベースとした時空間位相計測1)は、空間的な指向性を有するFWM光と励起光から分離した参照光との間で干渉系を構築することで実現した。干渉パターンをCCDにより検出し、2次元フーリエ変換を通して時間分解型のFWM信号を観測する。測定試料として、励起子束縛エネルギーが大きく、理想的な多準位系として異種励起子を扱える窒化ガリウム薄膜を用いた。異種励起子量子ビートと励起子-励起子分子量子ビートを観測したところ、2準位系と3準位系の励起子光学遷移にもとづくビート信号の違いを明らかにすることができた。並行して2)結晶のトポロジー変化に起因する電子状態の変化を明らかにすることを試みた。試料として特異なトポロジーを有する低次元導体を用いた。この物質は低温で電荷密度波と呼ばれる電子の集団励起状態を形成し、金属-絶縁体相転移を生じる。時間分解分光を用いて巨視的量子秩序形成を反映した電子応答変化を確認し、その温度依存性から結晶トポロジーによる有意な差を確認することに成功した。以上の結果にもとづき、3)より発展的なトポロジー計測を目的とした光渦パルスの発生を試みた。光渦パルスの評価は1)で確立した空間干渉をベースにし、時空間位相解析を実現した。光渦パルスとして50fs程度の短パルス生成に成功し、ドーナッツ状の強度分布と位相特異点の存在を明らかにした。また干渉振幅に着目すると、最大振幅を取る遅延時間が方位角に応じて変化していくことを見出した。
日本学術振興会, 萌芽研究, 北海道大学, 18656016

Multi-photon Absorption Spectroscopy for Three-dimensional Nanoscale Imaging of GaN
Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
2004 - 2006
TODA Yasunori, ADACHI Satoru, ARAKAWA Yasuhiko
Since strain and defects in semiconductors directly connect with the device performance, the influence has been studied extensively so far. Generally, there are various types of defects ranging from an atomic to a microscopic scale depending on the substrate, structure and growth conditions. In addition, the local strain fields due to mismatches in the lattice constants and the defects/impurities are also important for the thin films grown on foreign substrates. Therefore, three-dimensional (3D) analysis with a high spatial resolution is necessary for the precise characterization.
One approach to the optical characterization in 3D is the use of nonlinear processes, in which excitation well below the band-gap allows for cross-sectional analysis at any depth. Furthermore, the use of nonlinear spectroscopy often provides significant enhancement of the signal sensitivity. In this work, we demonstrated i) multiphoton induced absorption imaging and ii) four-wave mixing (FWM) spectroscopy for the precise characterization of Gallium Nitride (GaN) in terms of strain and defects. Both techniques developed here allow for nondestructive and noninvasive optical characterization not only for GaN but also for other semiconductor materials including nanostructures, which would be useful for diagnosing complex device structures.
In the two-photon absorption (TPA) imaging, we successfully mapped out the 3D distribution of defects with high spatial resolution. Moreover, using transient TPA measurements, we were able to obtain precise TPA coefficient that is one of the useful parameters for evaluating the optical damage threshold. In the GaN films, we showed that localized regions exist with significantly higher TPA coefficients, possibly due to the concentrations of defect states on a microscopic scale. In another nonlinear spectroscopy based on degenerate FWM technique, we successfully mapped out the local strain-field very precisely. Since the diffraction signal in FWM increases as the fourth power of the exciton oscillator strength, the exciton spectra show strong polarizations resulting from the uniaxial strain in the sample. The highly polarized spectra allow us to determine the precise splitting energy imposed by the local strain and defects. We measured various samples including GaN films on isotropic substrates, and examined the lower limit of detectable uniaxial strain, which is comparable with the resolution of conventional X-ray diffraction analysis.
Since the diffraction signal in FWM increases as the fourth power of the exciton oscillator strength, the exciton spectra show strong polarizations resulting from the uniaxial strain in the sample. The highly polarized spectra allow us to determine the precise splitting energy imposed by the local strain and defects. We measured various samples including GaN films on isotropic substrates, and examined the lower limit of detectable uniaxial strain, which is comparable with the resolution of conventional X-ray diffraction analysis.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), HOKKAIDO UNIVERSITY, 16310076

Spatio-temporally resolved observation and control of neuron excitement mechanism using nonlinear laser microscopes
Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
2004 - 2006
MORITA Ryuji, GOHARA Kazutoshi, TODA Yashinori
1.An over-one-octave spanning (460-1060 nm) ultra-broadband optical pulse was generated by self-modulation effect. It was spectrally-phase-compensated and characterized to be a 2.8 fs, 1.5 cycle-Fourier-transform-limited pulse by the modified spectral phase interferometry for direct electric-field reconstruction. It is the shortest visible and infrared pulse whose spectral phase is well determined.
2.A second-harmonic laser microscope was developed for 3-dimensional spatially-resolved observation of living cells. As an example, neurons of a rat were observed. Strong signals from nuclei and axons owing to inversion-symmetry breaking were detected. Spatial resolution was less than 1.5 μm.
3.A coherent anti-Stokes Raman scattering laser microscope was developed using a femtosecond laser amplifier as a light source. For onion cells, two pulses with wavelengths of 800 and 1040 nm were employed to excite the C-H vibration mode of 2900 cm-1 and the corresponding spatially-resolved signal with a wavelength of 650 nm was detected. Similarly, two pulses with wavelengths of 800 and 1100 nm were employed to excite the N-H vibration mode of 3400 cm-1 and the corresponding signal with a wavelength of 630 nm was detected. From comparison between those signals, C-H-and N-H-rich domains in cells were determined.
4.Macroscopic observation of hybridization and dehybridization for methylred-intercalated DNA was performed using second-harmonic laser microscope. While hybridized one has the inversion symmetry, dehybridized one does not. Significant signals were not obtained so far because of noise. Improvement is going on by introducing other azo-dyes with higher optical nonlinearity.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), HOKKAIDO UNIVERSITY, 16360024

Quantum computation using optical control of electron spins in quantum dots
Grants-in-Aid for Scientific Research
2002 - 2005
MUTO Shunichi, ADACHI Satoru, TODA Yasunori, SHIRAMINE Kenichi, YOH Kanji
An electron spin in a quantum dot is one of important candidates to be used for future large scale quantum computing. We have already proposed a set of universal quantum gates using photon-assisted tunneling and its coulomb blockade. In this project, we have done various experimental studies on the feasibility of this proposal. Also, the quantum computing is required to be connected to the photonic quantum infromation processing. Therefore we proposed a scheme to cunvert a photon qubit and an electron spin qubit and experimentally evaluated this proposal.
Before experiments, we did computer simulation of our universal gates and found that the experimental demonstration of the CNOT gateis possible ifthe coheraice of an electron spin is largo-than 100 ps.
Then, we developed a measurem ent technology based on the four-wave-mixing FWM to detarmine the electron spin coherence. We applied this to the spin relaxation measurements of electrons in a quantum well for which the pump -probe technique is established. The result of the new method, i.e. spin-diffracted FWM gave the same result as the pump -probe, indicating the validity of the method. We then, applied this to the ensemble of InAlAs/AlGaAs quantum dots and found that the longest coherence of these dots is as long as 7 ns. This value is much longer than those in the conventional method using streak-camera and indicates that the measurements of resonant excitation and dedection such as ours are necessary for precise determination of spin coherence instead of the non-resonant measurements such as those using streak-camers.
We also proposed a new qubit conversion scheme using the nuclear field to realize the degenerate electron levels and energy-split hole levels in a quantum dot. By exerimentally realizing the nuclear field by optically orienting the electron spins in an InAlAs/AlGaAs quantum dot, we found that we can realize the band structure for a qubit conversion between a photon and an dectron spin.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research on Priority Areas, Hokkaido Universigy, 14076201

Research on the coherent control of electron spins in quantum dots
Grants-in-Aid for Scientific Research
2002 - 2003
MUTO Shunichi, SHIRAMINE Kenichi, TODA Yasunori, ADACHI Satoru, TAKEUCHI Atsushi
Self-assembled InAlAs/AlGaAs quantum dots are grown by the Stranski-Krastanow mode of Molecular Beam Epitaxy (MBE). We measured the spin relaxation time of the structure under the non-resonant optical excitation by using 80 fs pulses by the titanium sapphire laser at wavelength of 780 nm. We used the right circular polarized light for the excitation of carrires to obtain fixed electron spins. The luminescence from the quantum dots at 10 K was divided into the right circular and the left circular components and was temporary resolved by the streak-scope. While the lifetime of the exciton was about 1 18 ns, the spin relaxation time determined by the decay of the polarization of luminescence was 1.31 us, which is comparable to the lifetime. The result indicates that the major relaxation mechanisms in the quantum well are not effective in the quantum dots and that the quantum dot is a good material for the coherent control of electron spins.
As the spin-electronisc material for the future generations, wide-gap semiconductors and a polymer was studied with emphasis on the magnetic or spintronic properties.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), HOKKAIDO UNIVERSITY, 14350001

Studies for estimation method of nonlinear optical crystals by using phonon imaging technique
Grants-in-Aid for Scientific Research
2001 - 2002
ADACHI Satoru, TANAKA Katsuhiko, TODA Yasunori
Im present work, we aimed the estimation of the crystal quality via the detection of the phonon scattering by the defect and so on by using our developed phonon-polariton imaging technique. We have performed the imaging experiment for the LiTaO_3. The phonon generation and monitoring of the propagating polariton wavepackets have been imaged. Illuminating the delayed pulse into the crystal in order to probe the generated phonon-polariton wavepackets, we could construct the image of the wavepackets at the real time within the temporal resolution of the used pulse. The phonon polariotn is really the modulation of the refractive indices and therefore the phase object. Although it is impossible usually to detect the phase of the scattered light since our detection ability is sensitive only to the intensity of the light, the conversion from the phase information to the intensity information can be achieved by using Talbot effect. We have succeeded to capture the interference of the phonon polariotn wavepackets at the real time via the special arrangement. Also we could control the amplitude of the propagating phonon polariton wavepacket within some extent. The obtained results can contribute greatly to the phonon spectroscopy and indicated the new direction of the research. By using the similar four-wave mixing technique, we could estimate the sample quality of the bulk GaN, which is the promising material for the laser diode and so on, via the phonon scattering and exciton-exciton interaction, and found the heterobiexciton. The hetero biexciton consists of the heavy-hole and light-hole excitons and we found the heterobiexciton in GaN for the first time.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 13554009

高空間分解多次元磁気光学応答計測技術の開発
科学研究費助成事業
2000 - 2001
大場 良次, 戸田 泰則
本研究の目的は、固体分光計測において高い空間分解能を有する走査型近接場光学顕微鏡(SNOM)の小型化を図り、外部装置との整合性を高め、空間的な多次元化を実現することである。本年度は、昨年度製作したSNOMを用いて、半導体量子ナノ構造の光学特性の取得と、その小型化を含めた多次元計測への応用を目標とした。
半導体量子ナノ構造を調査する目的として、制御性の高い量子ドットを測定対象とした。量子ドットではキャリアの自由度が全方向に制限されるため、ナノ領域の光物性として特異な性質を示すことが知られている。量子ドットを光励起すると、キャリアはまずドットの閉じ込めに起因する離散状態に励起され、発光再結合準位へと緩和し発光する。さらに今回試料として用いている自己形成量子ドットでは、周囲の媒質を反映した多くの局在フォノンモードが存在し、その緩和スペクトルはドットのキャリア閉じ込めと周囲の格子状態を反映することになる。したがって個々のドットの共鳴エネルギーに対して、その発光分布像を得ることにより、その共鳴がどのようなフォノンと結合しているか決定することが可能となる。今回の測定結果では、バルクのフォノンモードと、局在フォノンモードの共鳴エネルギーに対してそれぞれ異なる発光分布像が観測された。このことは自己形成量子ドットにおけるキャリア-フォノン結合状態の違いを意味しており、ヘテロ界面の重要性を明らかにしたものである。したがって空間的な多次元計測を達成すれば、より詳細な物性が明らかになると考えられる。この目的のために、いくつかの装置要素に対して小型化と多機能化を試みた。具体的にはイナーシャルスライダーの小型化、高さ制御ピエゾの小型化、光学機器の低減を達成した。装置の小型化は、機械的な安定性も向上させるため、上記の結果をもとにしたフォノンイメージングへと発展させることが可能となる。
日本学術振興会, 萌芽的研究, 北海道大学, 12875074

Coherent control of photo-excited carriers in semiconductor quantum dots using near-field scanning optical microscope
Grants-in-Aid for Scientific Research
2000 - 2001
TODA Yasunori
The strain-driven self-assembly of semiconductor quantum dots (SAQDs) provides nanometer scale carrier confinement in all three dimensions. One of the fascinating characteristics of SAQDs is their discrete density of states (DOS) with large energy-level spacing, in which acoustic phonon-mediated scattering should be suppressed compared with higher-dimensional structures. As a consequence, excitons in SAQDs are expected to exhibit long coherence time, which is advantageous for application of quantum information processing. In terms of inter-level relaxation, interaction with longitudinal optical (LO) phonons is an important aspect of SAQDs. These phonon-mediated transitions can be confirmed in the single-dot photoluminescence excitation (PLE) spectra, in which the reduction of relaxation paths renders individual LO phonons visible in the ground state emissions. To date several LO phonon-related transitions including bulk GaAs have been clearly observed. In the energy region higher than 1LO, single-dot PLE spectra reveal a number of intense PLE features, recognized as 2LO phonon resonances. As excitonic excited states are also present, several relaxation pathways with qualitatively different processes exist in the 2LO region.
In this research, we investigate in detail the 2LO resonances in the single-dot PLE. Several 2LO resonances emerge as dip structures in the peaks under various conditions of excitation power. The observed dip structures suggest line broadening, even in the individual resonace lines. In contrast, the corresponding biexciton resonances still have sharp peaks, indicating that the 2LO resonances consist of several relaxation channels with differing scattering processes. These observations can explain why PLE resonances exhibit short dephasing times even in single SAQDs. Moreover, we found that phonon mediated transitions can be largely removed by two-color excited PLE spectroscopy. The reduction of line broadening indicates that the PLE includes a number of phonon-related transitions with large relaxation windows.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 12650035