論文

• Keisuke Kawahara, Tai Tsuchizawa, Noritsugu Yamamoto, Yuriko Maegami, Koji Yamada, Shinsuke Hara, Toshihiko Baba. High-Efficiency Compact Optical Transmitter With a Total Bit Energy of 0.78 pJ/Bit Including Silicon Slow-Light Modulator and Open-Collector Current-Mode Driver, IEEE Journal of Selected Topics in Quantum Electronics, Mar. 2026.  公式リンク  
  
• 馬場俊彦, 川原啓輔. 光電融合設計による小型高性能マッハ・ツェンダー光変調器, 光学, vol. 54, no. 4, pp. 134-138, Apr. 2025.
• Keisuke Kawahara, Toshihiko Baba. Electro-Optic Co-Simulation in High-Speed Silicon Photonics Transceiver Design Using Standard Electronic Circuit Simulator, IEEE Journal of Microwaves, 2025.  公式リンク  
  
• Keisuke Kawahara, Tai Tsuchizawa, Noritsugu Yamamoto, Yuriko Maegami, Koji Yamada, Shinsuke Hara, Toshihiko Baba. High-speed, low-voltage, low-bit-energy silicon photonic crystal slow-light modulator with impedance-engineered distributed electrodes, Optica, Sept. 2024.  公式リンク  
  
• Keisuke Kawahara, Yohtaro Umeda, Kyoya Takano, Shinsuke Hara. A 0.0058-mm2 Inductor-Less CMOS Active Balun With Gain and Phase Errors Within −0.1 ± 0.2 dB and −0.18 ± 1.17° From DC to 8 GHz, IEEE Transactions on Circuits and Systems I: Regular Papers, June 2023.  公式リンク  
  
• Keisuke Kawahara, Joe Sawada, Takumi Kamo, Yohtaro Umeda, Kyoya Takano, Shinsuke Hara. Bandwidth Tripler: Broadband Signal Generation With an Image-Rejection Analog Multiplexer for Fiber Optic Transmitters, IEEE Transactions on Microwave Theory and Techniques, Jan. 2023.  公式リンク  
  
• Keisuke KAWAHARA, Yohtaro UMEDA, Kyoya TAKANO, Shinsuke HARA. A Compact Fully-Differential Distributed Amplifier With Coupled Inductors in 0.18-μm CMOS Technology, IEICE Transactions on Electronics, 2023.  公式リンク  
  

著書

• 川原 啓輔. 光電協調設計の最新動向, Optronics : 光技術コーディネートジャーナル, 東京 : オプトロニクス社, Vol. 44, No. 11, pp. 130-134, Nov. 2025.

国際会議発表 (査読有り)

• Toshihiko Baba, Keisuke Kawahara. Slow-light-based modulator and transmitter, Active Photonic Platforms (APP) 2025, Sept. 2025.  公式リンク  
  
• Keisuke Kawahara, Tai Tsuchizawa, Noritsugu Yamamoto, Yuriko Maegami, Koji Yamada, Shinsuke Hara, Toshihiko Baba. Optical Transmitter with Silicon Slow-Light Modulator and BiCMOS Current-Mode Driver Achieving 0.78 pJ/bit Total Bit Energy, OECC/PSC 2025, July 2025.
• Toshihiko Baba, Keisuke Kawahara. High-Efficiency Optical Transmitter Including Si Photonic Crystal Slow-Light Modulator Co-Designed with Driver Amplifier, 2025 30th OptoElectronics and Communications Conference (OECC) and 2025 International Conference on Photonics in Switching and Computing (PSC), June 2025.  公式リンク  
  
• Keisuke Kawahara, Toshihiko Baba. Accurate EO co-simulation of Si photonics using a standard electronic circuit simulator, Smart Photonic and Optoelectronic Integrated Circuits 2025, Mar. 2025.  公式リンク  
  
• Keisuke Kawahara, Toshihiko Baba. DAC- and DSP-Free Optical Transmitter Based on Triple-Parallel Si Mach-Zehnder Modulators, 2024 IEEE Silicon Photonics Conference (SiPhotonics), Apr. 2024.  公式リンク  
  
• Keisuke Kawahara, Tai Tsuchizawa, Noritsugu Yamamoto, Yuriko Maegami, Koji Yamada, Toshihiko Baba. 59-fJ/bit Si Photonic Crystal Slow-Light Modulator with FinFET-Compatible Driving Voltage, Optical Fiber Communication Conference (OFC) 2024, 2024.
• Kawahara, Keisuke, Tsuchizawa, Tai, Yamamoto, Noritsugu, Maegami, Yuriko, Yamada, Koji, Hara, Shinsuke, Baba, Toshihiko, Keisuke Kawahara. 1.9-pJ/bit 0.5-mm2 High-Speed Optical Transmitter including Silicon Slow-Light Modulator and Current-Mode BiCMOS Driver, ECOC 2024; 50th European Conference on Optical Communication, pp. 778-781, 2024.  公式リンク  
  
• Keisuke Kawahara, Toshihiko Baba. Modeling of Si Rib and Photonic Crystal Mach-Zehnder Modulators for Electro-Optic Co-Simulation up to 64 Gbaud, 2023 IEEE MTT-S International Conference on Numerical Electromagnetic and Multiphysics Modeling and Optimization (NEMO), Aug. 2023.  公式リンク  
  
• Keisuke Kawahara, Keisuke Kawahara, Joe Sawada, Takumi Kamo, Yohtaro Umeda, Kyoya Takano. A 50 Gbps 49 mW CMOS Analog Multiplexer for a DAC Bandwidth Tripler, 2022 IEEE Radio and Wireless Symposium (RWS), Jan. 2022.  公式リンク  
  
• Keisuke Kawahara, Keisuke Kawahara, Yohtaro Umeda, Kyoya Takano. A Broadband Active Balun with Inductor-Less Active Peaking and Imbalance Correction, 2021 IEEE International Midwest Symposium on Circuits and Systems (MWSCAS), Aug. 2021.  公式リンク  
  
• Keisuke Kawahara, Keisuke Kawahara, Yohtaro Umeda, Kyoya Takano. Design of an Area-Efficient Differential Distributed Amplifier Based on the Theory of Differential Transmission Lines, 2021 IEEE International Symposium on Circuits and Systems (ISCAS), May 2021.  公式リンク  
  
• Keisuke Kawahara, Keisuke Kawahara, Yohtaro Umeda, Kyoya Takano. 40 Gbps 180 nm CMOS Modulator Driver Using Loss Compensation Gain Cells, 2020 IEEE International Symposium on Radio-Frequency Integration Technology (RFIT), Sept. 2020.  公式リンク  
  

国内会議発表 (査読なし・不明)

• Haoyu Chen, Moataz Eissa, Kaibin Yao, Tsuyoshi Horikawa, Keisuke Kawahara, Nobuhiko Nishiyama. High-Efficiency Vertical Coupler between Si and Low-index (~1.6) SiON Waveguide with Low Polarization Dependance Loss, The 73rd JSAP Spring Meeting 2026, Mar. 2026.
• 川原啓輔, 土澤泰, 山本宗継, 前神有里子, 山田浩治, 馬場俊彦. 光電気等化によるSiフォトニック結晶光変調器の100 Gbaud動作, 応用物理学会 秋季学術講演会, Sept. 2025.
• 川原 啓輔, 鎌田 幹也, 雛倉 陽介, 岡野 誠, Cong Guangwei, 山本 宗継, 山田 浩治, 馬場 俊彦. 64 Gbps Si フォトニック結晶光変調器の変調効率改善, 応用物理学会学術講演会講演予稿集, 公益社団法人 応用物理学会, Vol. 2022.2, No. 0, pp. 1175-1175, July 2022.

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