First demonstration of PDM signal amplification using PPLN-based polarization-independent phase sensitive amplifier. - Takeshi Umeki; Takushi Kazama; Osamu Tadanaga; Koji Enbutsu; Masaki Asobe; Yutaka Miyamoto; Hirokazu Takenouchi (ECOC, 2014)

Spectrally efficient optical phase conjugation based on complementary spectral inversion for nonlinearity mitigation. - Takeshi Umeki; Takushi Kazama; H. Ono; Yutaka Miyamoto; Hirokazu Takenouchi (ECOC, 2015)

Low-noise phase-sensitive amplifier for guard-band-less 16-channel DWDM signal using PPLN waveguides. - Takushi Kazama; Takeshi Umeki; Masashi Abe; Koji Enbutsu; Yutaka Miyamoto; Hirokazu Takenouchi (OFC, 2016)

Towards Practical Implementation of Optical Parametric Amplifiers Based on PPLN Waveguides. - Takeshi Umeki; Takushi Kazama; Takayuki Kobayashi; Koji Enbutsu; Osamu Tadanaga; Hirokazu Takenouchi; Ryoichi Kasahara; Yutaka Miyamoto (OFC, 2018)

Polarization-diversity In-line Phase Sensitive Amplifier for Simultaneous Amplification of Fiber-transmitted WDM PDM-16QAM Signals. - Takeshi Umeki; Takushi Kazama; Takayuki Kobayashi; Shigehiro Takasaka; Yasuhiro Okamura; Koji Enbutsu; Osamu Tadanaga; Hirokazu Takenouchi; Ryuichi Sugizaki; Atsushi Takada; Ryoichi Kasahara; Yutaka Miyamoto (OFC, 2018)

Low-Noise Phase Sensitive Amplification Using an Optical Phase-Locked Pump. - Takushi Kazama; Takeshi Umeki; Yasuhiro Okamura; Koji Enbutsu; Osamu Tadanaga; Atsushi Takada; Ryoichi Kasahara (OECC/PSC, 2019)

1.4μm-1.6μm Wavelength Conversion Using Multiple Quasi-Phase Matching LiNbO3. - Saroeun Punhavan; Masato Kato; Keisuke Sugiyama; Masaki Asobe; Takeshi Umeki; Koji Enbutsu; Takushi Kazama; Takahiro Kashiwazaki; Ryoichi Kasahara (OECC/PSC, 2019)

Nonlinearity mitigation of PDM-16QAM signal using multiple CSI-OPCs in ultra-long haul transmission without excess penalty. - Takeshi Umeki; Takayuki Kobayashi; Akihide Sano; Takuya Ikuta; Masashi Abe; Takushi Kazama; Koji Enbutsu; Ryoichi Kasahara; Yutaka Miyamoto (OECC/PSC, 2019)

Wideband Inline-Amplified WDM Transmission using PPLN-Based OPA with Over-10-THz Bandwidth. - Takayuki Kobayashi; Shimpei Shimizu; Masahito Nakamura; Takeshi Umeki; Takushi Kazama; Ryoichi Kasahara; Fukutaro Hamaoka; Munehiko Nagatani; Hiroshi Yamazaki; Takayuki Mizuno; Hideyuki Nosaka; Yutaka Miyamoto (OFC, 2020)

Gain Ripple and Passband Narrowing Due to Residual Chromatic Dispersion in Non-Degenerate Phase-Sensitive Amplifiers. - Shimpei Shimizu; Takushi Kazama; Takayuki Kobayashi; Takeshi Umeki; Koji Enbutsu; Ryoichi Kasahara; Yutaka Miyamoto (OFC, 2020)

PPLN-Based Low-Noise Phase Sensitive Amplification Using an Optical Phase-Locked Pump. - Takushi Kazama; Takeshi Umeki; Yasuhiro Okamura; Koji Enbutsu; Osamu Tadanaga; Atsushi Takada; Ryoichi Kasahara (IEICE Trans. Commun., 2020)

Nonlinearity Mitigation of PDM-16QAM Signals Using Multiple CSI-OPCs in Ultra-Long-Haul Transmission without Excess Penalty. - Takeshi Umeki; Takayuki Kobayashi; Akihide Sano; Takuya Ikuta; Masashi Abe; Takushi Kazama; Koji Enbutsu; Ryoichi Kasahara; Yutaka Miyamoto (IEICE Trans. Commun., 2020)

13.4-Tb/s WDM Transmission over 1, 280 km Repeated only with PPLN-based Optical Parametric Inline Amplifier. - Takayuki Kobayashi; Shimpei Shimizu; Masanori Nakamura; Takushi Kazama; Takeshi Umeki; Ryoichi Kasahara; Fukutaro Hamaoka; Yutaka Miyamoto (ECOC, 2021)

8-Tbps (20 × 400 Gbps) Unrepeated Transmission over 80 km with 2-THz PPLN-Based Phase-Sensitive Amplification Using Precise Chromatic Dispersion Pre-Compensation. - Shimpei Shimizu; Takayuki Kobayashi; Takushi Kazama; Takeshi Umeki; Masanori Nakamura; Koji Enbutsu; Ryoichi Kasahara; Yutaka Miyamoto (ECOC, 2021)

Wideband PPLN-based optical parametric amplifiers for scalable optical transport network. - Yutaka Miyamoto; Takayuki Kobayashi; Takeshi Umeki; Takushi Kazama; Koji Enbutsu; Shimpei Shimizu; Ryoichi Kasahara (OFC, 2021)

50-Tb/s (1 Tb/s × 50 ch) WDM Transmission on Two 6.25-THz Bands Using Hybrid Inline Repeater of PPLN-based OPAs and Incoherent-forward-pumped DRA. - Takayuki Kobayashi; Shimpei Shimizu; Masanori Nakamura; Takeshi Umeki; Takushi Kazama; Junji Yoshida; Shigehiro Takasaka; Yasuto Tatamida; Hiroto Kawakami; Fukutaro Hamaoka; Munehiko Nagatani; Hiroshi Yamazaki; et al. (OFC, 2022)

Mitigation of Intercore Crosstalk Impact with PPLN-based Optical Spectrum Inversion. - Megumi Hoshi; Kohki Shibahara; Shimpei Shimizu; Takayuki Kobayashi; Takeshi Umeki; Takushi Kazama; Kei Watanabe; Takayoshi Mori; Yusuke Yamada; Kazuhide Nakajima; Yutaka Miyamoto (OECC/PSC, 2022)

WDM Transmission in S-Band Using PPLN-Based Wavelength Converters and 400-Gb/s C-Band Real-Time Transceivers. - Tomoyuki Kato; Hidenobu Muranaka; Yu Tanaka; Yuichi Akiyama; Takeshi Hoshida; Shimpei Shimizu; Takayuki Kobayashi; Takushi Kazama; Takeshi Umeki; Kei Watanabe; Yutaka Miyamoto (OECC/PSC, 2022)

Generation of Carrier-Synchronized PDM Signal-Idler Pair for Polarization-Independent Phase-Sensitive Amplification. - Shimpei Shimizu; Takushi Kazama; Takeshi Umeki; Takayuki Kobayashi; Koji Enbutsu; Kei Watanabe; Yutaka Miyamoto (OECC/PSC, 2022)

Channel Arrangement Design in Lumped Amplified WDM Transmission over NZ-DSF Link with Nonlinearity Mitigation Using Optical Phase Conjugation. - Shimpei Shimizu; Takayuki Kobayashi; Takeshi Umeki; Takushi Kazama; Koji Enbutsu; Ryoichi Kasahara; Yutaka Miyamoto (IEICE Trans. Commun., 2022)

103-ch. 132-Gbaud PS-QAM Signal Inline-amplified Transmission with 14.1-THz Bandwidth Lumped PPLN-based OPAs over 400-km G.652.D SMF. - Takayuki Kobayashi; Shimpei Shimizu; Masanori Nakamura; Takushi Kazama; Masashi Abe; Takeshi Umeki; Akira Kawai; Fukutaro Hamaoka; Munehiko Nagatani; Hiroshi Yamazaki; Yutaka Miyamoto (OFC, 2023)

Experimental Demonstration of Cascadable PPLN-Based Inter-Band Wavelength Converters for Band-Switchable Multi-Band Optical Cross-Connect. - Haruka Minami; Kenta Hirose; Takafumi Fukatani; Masahiro Nakagawa; Takeshi Seki; Shimpei Shimizu; Takayuki Kobayashi; Takushi Kazama; Koji Enbutsu; Kei Watanabe; Takeshi Umeki; Takashi Miyamura; et al. (OFC, 2023)

38.4-Tbps Inline-amplified Transmission Using PPLN-based Optical Parametric Amplifier over 6 THz within L- and U-bands. - Shimpei Shimizu; Takayuki Kobayashi; Akira Kawai; Takushi Kazama; Masanori Nakamura; Koji Enbutsu; Takahiro Kashiwazaki; Masashi Abe; Takeshi Umeki; Yutaka Miyamoto; Tomoyuki Kato; Yu Tanaka; et al. (OFC, 2023)

S-Band WDM Transmission Using PPLN-Based Wavelength Converters and 400-Gb/s C-Band Real-Time Transceivers. - Tomoyuki Kato; Hidenobu Muranaka; Yu Tanaka; Yuichi Akiyama; Takeshi Hoshida; Shimpei Shimizu; Takayuki Kobayashi; Takushi Kazama; Takeshi Umeki; Kei Watanabe; Yutaka Miyamoto (IEICE Trans. Commun., 2023)

C+L+U-Band 14.85-THz WDM Transmission Over 80-km-Span G.654.E Fiber with Hybrid PPLN-OPA/EDFA U-Band Lumped Repeater Using 144-Gbaud PCS-QAM Signals. - Takayuki Kobayashi; Shimpei Shimizu; Akira Kawai; Masanori Nakamura; Masashi Abe; Takushi Kazama; Takeshi Umeki; Munehiko Nagatani; Kosuke Kimura; Hitoshi Wakita; Yuta Shiratori; Fukutaro Hamaoka; et al. (OFC, 2024)

Cascadability of PPLN-Based Inter-Band Wavelength Conversion for Band-Switchable Multi-Band Optical Cross-Connect. - Haruka Minami; Takafumi Fukatani; Masahiro Nakagawa; Takeshi Seki; Shimpei Shimizu; Takayuki Kobayashi; Takushi Kazama; Koji Enbutsu; Takeshi Umeki; Rie Hayashi; Takeshi Kuwahara (OFC, 2024)

Modeling and Experimental Verification in S+C+L+U Quadrable-Band WDM Transmission System using C+L-Band Transceivers and Wavelength Converters. - Hidenobu Muranaka; Tomoyuki Kato; Tomohiro Yamauchi; Hiroyuki Irie; Hiroki Ooi; Yu Tanaka; Shimpei Shimizu; Takayuki Kobayashi; Takushi Kazama; Masashi Abe; Takeshi Umeki; Yutaka Miyamoto; et al. (OFC, 2024)

PPLN-Based Polarization-Diverse Phase-Sensitive Amplification of 96-Gbaud PDM-PCS-64QAM Signal with Carrier-Phase-Locked Phase-Conjugated Twin Waves. - Shimpei Shimizu; Takushi Kazama; Takeshi Umeki; Koji Enbutsu; Masanori Nakamura; Masashi Abe; Takayuki Kobayashi; Yutaka Miyamoto (OFC, 2024)

9-THz Wideband PPLN-Based Wavelength Converter for Simultaneous Conversion of C+L-Band WDM Signal to Full S-Band. - Shunya Konno; Shimpei Shimizu; Masashi Abe; Takushi Kazama; Koji Enbutsu; Takahiro Kashiwazaki; Masanori Nakamura; Takayuki Kobayashi; Yutaka Miyamoto; Takeshi Umeki (OFC, 2025)

27-THz ISRS-Supported Transmission Over 1040 km in S+C+L+U and Extreme Longer-Wavelength Band. - Shimpei Shimizu; Kosuke Kimura; Akira Kawai; Masashi Abe; Shunya Konno; Takushi Kazama; Masanori Nakamura; Fukutaro Hamaoka; Koji Enbutsu; Takahiro Kashiwazaki; Munehiko Nagatani; Hitoshi Wakita; et al. (OFC, 2025)