論文 - 神成　文彦

Ultrafast single-shot burst imaging in a few-nanosecond window using a spectrally sweeping laser pulse train

Nemoto H., Suzuki T., Matsushita K., Takasawa K., Kannari F.

2019 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2019 （2019 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2019）  2019年06月

研究論文（学術雑誌）, 査読有り,  ISSN  9781728104690

　概要を見る

© 2019 IEEE. To capture ultrafast non-repeatable phenomena, we had developed two methods of single-shot ultrafast two-dimensional (2D)-imaging of sequentially timed all-optical mapping photography (STAMP) [1] and STAMP utilizing spectral filtering (SF-STAMP) [2, 3]. In these STAMP schemes, spectral images measured by a linearly frequency-chirped laser pulse corresponds to time-resolved snapshots. So far, we achieved single-shot burst imaging of ultrafast phenomena in picosecond time windows with sub-picosecond temporal resolutions. However, it is not straightforward to extend the time window beyond 10 ps by a conventional method to chirp the probe laser pulse using material dispersion. Currently, we applied a new scheme of free-space angular-chirp-enhanced delay (FACED) [4] composed of a tilted pair of mirrors to SF-STAMP and achieved a sub-ns time window [5]. In this work, we generated spectrally sweeping burst pulses with a 300-ps-pulse interval by FACED, and captured singleshot ultrafast 2D-burst images with a few-nanosecond time window. Furthermore we combined a 1-kfps fast camera. Repetitive laser ablation was captured with 10-frame, 300-ps interval images at every 1 ms.

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The first demonstration of a 639-nm regenerative laser amplifier

Sugiyama N., Fujita S., Hara Y., Kannari F.

2019 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2019 （2019 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2019）  2019年06月

研究論文（学術雑誌）, 査読有り,  ISSN  9781728104690

　概要を見る

© 2019 IEEE. High-power picosecond lasers in the visible and ultraviolet wavelength hold a lot of advantages in various applications. The high absorption efficiency in the various metals leads to the higher removal rates, and the shorter pulse widths can suppress thermal influence during the material processing. Recently, the significant progress in the output power of indium gallium nitride (InGaN)-based laser diodes (LDs) has developed the compact high-power lasers which oscillate directly in the visible wavelength. For example, a continuous-wave laser output power of >6.7 W at the fundamental wavelength of 639 nm was reported with a praseodymium-doped LiYF4 crystal (Pr:YLF) [1]. Moreover, mode-locked picosecond lasers were also reported using a SESAM saturable absorber with Pr:YLF lasers [2,3]. Further scaling of visible picosecond laser pulse requires an amplifier, but only few experiments were reported on the visible laser amplifiers [4]. For example, the maximum amplification factor of 10 was demonstrated at 478 nm [5]. In this paper, a 639-nm picosecond-pulse regenerative amplifier using a Pr:YLF crystal is demonstrated for the first time.

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Single-shot 2-D burst ultrafast THz imaging utilizing SF-STAMP

Takasawa K., Yamaguchi Y., Nemoto H., Suzuki T., Tani M., Kitahara H., Bulgarevich D.S., Kannari F.

2019 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2019 （2019 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2019）  2019年06月

研究論文（学術雑誌）, 査読有り,  ISSN  9781728104690

　概要を見る

© 2019 IEEE. Since terahertz (THz) electromagnetic wave exhibits high transparency for various matters and can probe fingerprint spectra of various substances, THz imaging is expected for various quality inspections. Thus, it is desireble to capture 2-D images without spatial scanning. Moreover, if we can capture 2-D burst images of ultrafast transient phenomena in a single shot basis, it will be a powerful tool to understand the response of matters under high electric fields. However, with the conventional terahertz imaging method[1], iterative measurements are always required for capturing dynamic 2-D images.

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Ultrafast single-shot burst imaging in a few-nanosecond window using a spectrally sweeping laser pulse train

Nemoto H., Suzuki T., Matsushita K., Takasawa K., Kannari F.

Optics InfoBase Conference Papers （Optics InfoBase Conference Papers）  Part F140-CLEO_Europe 2019 2019年

研究論文（学術雑誌）, 査読有り,  ISSN  9781557528209

　概要を見る

© 2019 IEEE To capture ultrafast non-repeatable phenomena, we had developed two methods of single-shot ultrafast two-dimensional (2D)- imaging of sequentially timed all-optical mapping photography (STAMP) [1] and STAMP utilizing spectral filtering (SF-STAMP) [2, 3]. In these STAMP schemes, spectral images measured by a linearly frequency-chirped laser pulse corresponds to time-resolved snapshots. So far, we achieved single-shot burst imaging of ultrafast phenomena in picosecond time windows with sub-picosecond temporal resolutions. However, it is not straightforward to extend the time window beyond 10 ps by a conventional method to chirp the probe laser pulse using material dispersion. Currently, we applied a new scheme of free-space angular-chirp-enhanced delay (FACED) [4] composed of a tilted pair of mirrors to SF-STAMP and achieved a sub-ns time window [5]. In this work, we generated spectrally sweeping burst pulses with a 300-ps-pulse interval by FACED, and captured single-shot ultrafast 2D-burst images with a few-nanosecond time window. Furthermore we combined a 1-kfps fast camera. Repetitive laser ablation was captured with 10-frame, 300-ps interval images at every 1 ms.

The first demonstration of a 639-nm regenerative laser amplifier

Sugiyama N., Fujita S., Hara Y., Kannari F.

Optics InfoBase Conference Papers （Optics InfoBase Conference Papers）  Part F140-CLEO_Europe 2019 2019年

研究論文（学術雑誌）, 査読有り,  ISSN  9781557528209

　概要を見る

© 2019 IEEE High-power picosecond lasers in the visible and ultraviolet wavelength hold a lot of advantages in various applications. The high absorption efficiency in the various metals leads to the higher removal rates, and the shorter pulse widths can suppress thermal influence during the material processing. Recently, the significant progress in the output power of indium gallium nitride (InGaN)-based laser diodes (LDs) has developed the compact high-power lasers which oscillate directly in the visible wavelength. For example, a continuous-wave laser output power of >6.7 W at the fundamental wavelength of 639 nm was reported with a praseodymium-doped LiYF4 crystal (Pr:YLF) [1]. Moreover, mode-locked picosecond lasers were also reported using a SESAM saturable absorber with Pr:YLF lasers [2,3]. Further scaling of visible picosecond laser pulse requires an amplifier, but only few experiments were reported on the visible laser amplifiers [4]. For example, the maximum amplification factor of 10 was demonstrated at 478 nm [5]. In this paper, a 639-nm picosecond-pulse regenerative amplifier using a Pr:YLF crystal is demonstrated for the first time.

Single-shot 2-D burst ultrafast THz imaging utilizing SF-STAMP

Takasawa K., Yamaguchi Y., Nemoto H., Suzuki T., Tani M., Kitahara H., Bulgarevich D.S., Kannari F.

Optics InfoBase Conference Papers （Optics InfoBase Conference Papers）  Part F140-CLEO_Europe 2019 2019年

研究論文（学術雑誌）, 査読有り,  ISSN  9781557528209

　概要を見る

© 2019 IEEE Since terahertz (THz) electromagnetic wave exhibits high transparency for various matters and can probe fingerprint spectra of various substances, THz imaging is expected for various quality inspections. Thus, it is desireble to capture 2-D images without spatial scanning. Moreover, if we can capture 2-D burst images of ultrafast transient phenomena in a single shot basis, it will be a powerful tool to understand the response of matters under high electric fields. However, with the conventional terahertz imaging method[1], iterative measurements are always required for capturing dynamic 2-D images.

Measurement of propagation of ultrafast surface plasmon polariton pulses using dual-probe scanning near-field optical microscopy

Masaki Y., Tomita K., Kojima Y., Kannari F.

Applied Optics （Applied Optics）  58 （ 21 ） 5595 - 5601 2019年

研究論文（学術雑誌）, 査読有り,  ISSN  1559128X

　概要を見る

© 2019 Optical Society of America We report the construction of diagnostics for ultrafast surface plasmon polariton (SPP) pulses that evolve spatiotemporally in femtosecond and nanometer scales. We constructed two types of scanning near-field optical microscopes (SNOMs) and verified that the temporal waveform of ultrafast SPP pulses can be measured by combining spectral interferometry (SI). In the illumination-collection (I-C) mode SNOM, which uses a single fiber probe to excite samples and collect optical responses, a lock-in detection scheme using a lock-in camera detects SI fringes even for extremely weak signal light pulses. With this I-C SI-SNOM scheme, we measured the complex plasmon response functions of gold (Au) nanorods on Ge2Sb2Te5 thin film, both in the crystal and amorphous phases. For a dual-probe SNOM (DSNOM), a dual-band modulation technique was introduced to independently control the probe-sample and probe–probe distances. With the DSNOM and by employing femtosecond SPP pulse excitation, we successfully measured the temporal waveform of an ultrafast SPP pulse that is propagating on an Au thin layer.

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Intracavity second-harmonic pulse generation at 261 and 320 nm with a Pr³⁺:YLF laser Q-switched by a Co²⁺:MgAl<inf>2</inf>O<inf>4</inf> spinel saturable absorber

Fujita S., Tanaka H., Kannari F.

Optics Express （Optics Express）  27 （ 26 ） 38134 - 38146 2019年

研究論文（学術雑誌）, 査読有り

　概要を見る

© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement. We demonstrated the power scaling of a passively Q-switched Pr3+:LiYF4 (YLF) laser at 523, 607, and 640 nm with a Co2+:MgAl2O4 (MALO) saturable absorber and analyzed the experimental results with a numerical simulation based on rate equations. A maximum pulse energy of 33.5 µJ was obtained with a pulse width of 30.9 ns and a repetition rate of 64.0 kHz at 640 nm. We demonstrated ultraviolet pulse generation at 261 and 320 nm by intracavity frequency doubling and obtained 63.3-ns pulses with a pulse energy of 7.0 µJ and a repetition rate of 64.6 kHz at 320 nm as well as 356-ns 261-nm pulses with a pulse energy of 0.2 µJ at a repetition rate of 82.0 kHz. To the best of our knowledge, a 261-nm pulse is the shortest wavelength laser directly generated from the intracavity second-harmonic generation of passively Q-switched lasers.

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Frequency-domain linear interferometer with spectrally shaped photons

Hosaka A., Tomita M., Tsujimoto Y., Niimura S., Omi A., Wakui K., Fujiwara M., Shikano Y., Takeoka M., Kannari F.

Optics InfoBase Conference Papers （Optics InfoBase Conference Papers）  Part F143-EQEC 2019 2019年

研究論文（学術雑誌）, 査読有り,  ISSN  9781557528209

　概要を見る

© 2019 IEEE Beam splitters and phase shifters compose linear photonic circuits and are the most fundamental elements in photon-based quantum information processing. While integration of these linear components on a chip for spatial modes has been dramatically developed in recent years [1], there is another approach for integrated quantum circuits: wavelength division multiplexing (WDM). The degrees of freedom of light allow photons exhibiting different wavelengths to exist independently in the same space, therefore using such characteristics can allow further integrating of photons and modes in a small space.

Diode-pumped Picosecond 640-nm Pr:YLF Regenerative Laser Amplifier

Kannari F., Hara Y., Sugiyama N., Fujita S., Tanaka H.

Optics InfoBase Conference Papers （Optics InfoBase Conference Papers）  Part F139-ASSL 2019 2019年

研究論文（学術雑誌）, 査読有り,  ISSN  9781557528209

　概要を見る

© 2019 The Author(s) We demonstrated generative picosecond laser pulse amplification at 640 nm for the first time using a Pr3+:YLF crystal, which was continuously pumped by an InGaN diode laser, with a mode-locked Pr3+:YLF oscillator.

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Diode-pumped 640 nm Pr:YLF regenerative laser pulse amplifier

Sugiyama N., Fujita S., Hara Y., Tanaka H., Kannari F.

Optics Letters （Optics Letters）  44 （ 13 ） 3370 - 3373 2019年

研究論文（学術雑誌）, 査読有り,  ISSN  01469592

　概要を見る

© 2019 Optical Society of America We demonstrated regenerative laser pulse amplification at 640 nm for the first time, to the best of our knowledge, with a mode-locked Pr3-doped LiYF4 (Pr3:YLF) oscillator as a picosecond seed pulse. A regenerative amplifier with a Pr3:YLF crystal was continuously pumped by a multi-mode InGaN diode laser. At an absorbed pump power of 3.1 W, we obtained amplified pulse energy of 13 μJ at 10 kHz with an excellent spatial beam quality of M 2∼1.1, demonstrated second-harmonic generation, and obtained a 320 nm pulse energy of 5.9 μJ.

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Shaping and amplification of wavelength-tunable mid-infrared femtosecond pulses generated by intra-pulse difference-frequency mixing with spectral focusing

神成 文彦

Journal of the Optical Society of America B: Optical Physics （Journal of the Optical Society of America B: Optical Physics）  35 （ 12 ） C1 - C7 2018年09月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  07403224

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希ガス中空ファイバで広帯域化された超広帯域フェムト秒レーザーの短波長帯と長波長帯を周波数チャープさせて時間遅延をつけて重畳することで、type-I　BBO結晶で差周波発生を行うことで、中心周波数およびバンド幅可変の中赤外レーザー発生が可能であることを実験から明らかにし、さらにOPAで増幅し分光応用可能な出力レベルを確保できることを実証した。

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Transition-metal-doped solid-state saturable absorbers for passively Q-switched visible Pr:YLF lasers

Tanaka H., Castellano-Hernandez E., Krankel C., Kannari F.

2018 Conference on Lasers and Electro-Optics, CLEO 2018 - Proceedings （2018 Conference on Lasers and Electro-Optics, CLEO 2018 - Proceedings）  2018年08月

ISSN  9781943580422

　概要を見る

© 2018 OSA. We report the first visibly emitting Q-switched laser based on Co2+:Gd3Ga5O12as the saturable absorber material and present a detailed characterization of the visible saturable absorption properties of various Co2+-doped materials.

High-power visibly emitting Pr³⁺:YLF laser end pumped by single-emitter or fiber-coupled GaN blue laser diodes

Tanaka H., Fujita S., Kannari F.

Applied Optics （Applied Optics）  57 （ 21 ） 5923 - 5928 2018年07月

研究論文（学術雑誌）, 査読有り,  ISSN  1559128X

　概要を見る

© 2018 Optical Society of America. We demonstrate the high-power continuous-wave operation of a Pr3:YLF laser end pumped by blue laser diodes. As the pump source, we used four 5 W single-emitter blue laser diodes and a >20 W fiber-coupled module. In single-emitter-diode pumping, we obtained pump-limited output powers of 6.7 and 3.7 W at 640 and 607 nm, respectively. We successfully suppressed thermal aberration and obtained an output power of 3.4 W at a slope efficiency of 25% at 640 nm with good beam quality in the fiber-coupled module pumping.

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High-power visibly emitting Pr3+:YLF laser end pumped by single-emitter or fiber-coupled GaN blue laser diodes

神成 文彦

Applied Optics （OSA）  57 （ 21 ） 5923 - 5928 2018年07月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

出力５WのInGaN青色半導体レーザー４台、また２０Wのマルチモードファイバ出射青色半導体レーザーを用いた端面励起Pr:YLF可視レーザーの出力スケーリング実験を行い、熱負荷特性からPr:YLFレーザーの特性を考察した。出力的には、これまで最高の6.7,
3.7 Wをk各640 ,607 nmにおいて達成できた。

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Design of a Multistage Quantum Pulse Gate in the Frequency Domain

Niimura S., Hosaka A., Tomita M., Omi A., Kannari F.

2018 Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2018 （2018 Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2018）  2018年07月

研究論文（学術雑誌）, 査読有り,  ISSN  9781943580453

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© 2018 OSA. We propose a multistage quantum pulse gate which efficiently mix multimode quantum states in the frequency domain. Furthermore we introduce a practicable quantum simulator for calculating Frank Condon factors.

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Single-Shot Ultrafast Burst Imaging by Spectrally Sweeping Pulse Train with 100-Ps Interval

Nemoto H., Suzuki T., Yamaguchi Y., Kannari F.

2018 Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2018 （2018 Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2018）  2018年07月

研究論文（学術雑誌）, 査読有り,  ISSN  9781943580453

　概要を見る

© 2018 OSA. We generate a spectrally sweeping 100-ps-interval pulse train for ultrafast burst imaging. Adopting those pulses to sequentially timed all-optical mapping photography utilizing spectral filtering (SF-STAMP), we realize single-shot burst imaging with a sub-nanosecond time window.

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Selective Nano-Cars Microscopy with Dual-Wavelength Nanofocused Ultrafast Plasmon Pulses

Tomita K., Kannari F.

2018 Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2018 （2018 Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2018）  2018年07月

研究論文（学術雑誌）, 査読有り,  ISSN  9781943580453

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© 2018 OSA. We demonstrate selective CARS measurements of a monolayer graphene and multi-walled carbon nanotubes (MWCNT)at the D-, G-, and 2D-bands with nanofocused SPP pulses at 800 and 440 nm using an aluminum tapered tip.

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Homodyne Detection of 1.57-μm Squeezed Vacuum Pulse with Degenerate Optical Parametric Oscillator Pumped by a Common 785-Nm Laser

Omi A., Hosaka A., Tomita M., Niimura S., Kannari F.

2018 Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2018 （2018 Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2018）  2018年07月

研究論文（学術雑誌）, 査読有り,  ISSN  9781943580453

　概要を見る

© 2018 OSA. We generate 1.57-μm squeezed vacuum pulses by degenerate spontaneous parametric down conversion (DSPDC)and observe 3.5dB anti-squeezing and -0.48dB squeezing using local oscillator pulses generated from a degenerate synchronously pumped optical parametric oscillator.

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Mode-locked Ti:sapphire laser oscillators pumped by wavelength-multiplexed laser diodes

Sugiyama N., Tanaka H., Kannari F.

Japanese Journal of Applied Physics （Japanese Journal of Applied Physics）  57 （ 5 ） 052701-1 - 052701-4 2018年03月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  00214922

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© 2018 The Japan Society of Applied Physics. We directly pumped a Ti:sapphire laser by combining 478 and 520 nm laser diodes to prevent the effect of absorption loss induced by the pump laser of shorter wavelengths (>450 nm). We obtain a continuous-wave output power of 660 mW at a total incident pump power of 3.15 W. We demonstrate mode locking using a semiconductor saturable absorber mirror, and 126 fs pulses were obtained at a repetition rate of 192 MHz. At the maximum pump power, the average output power is 315 mW. Shorter mode-locked pulses of 42 and 48 fs were respectively achieved by Kerr-lens mode locking with average output powers of 280 and 360 mW at a repetition rate of 117 MHz.

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