光電流を従来の340倍に増幅する超小型光回路モニタを開発 ～ AIデータセンターやLiDAR向け光回路を高精度化～

2026-03-19 早稲田大学

図：マルチモード干渉を利用した光回路モニタ

＜関連情報＞

• https://www.waseda.jp/inst/research/news/83833
• https://ieeexplore.ieee.org/document/11421590

シリコンフォトニック集積回路向けマルチモード干渉に基づく小型・超低損失インライン光パワーモニタ Compact and Ultra-Low-Loss Inline Optical Power Monitor Based on Multimode Interference for Silicon Photonic Integrated Circuits

Tomohiro Kita; Kiyoharu Tsujishita
Journal of Lightwave Technology  Published:04 March 2026
DOI:https://doi.org/10.1109/JLT.2026.3670843

Abstract

We propose and experimentally demonstrate an ultrasmall, low-loss inline photodetector based on multimode interference in a silicon multimode waveguide. Periodic self-focusing enables heavily doped electrodes to be placed close to the waveguide with negligible loss. The detector provides <0.1 dB insertion loss over a wide wavelength range with a total length of 4.7 μm. Owing to photoconductive operation, short electrode spacing, and a photoconductive gain of approximately 340, a sensitivity of 75 mV/mW is achieved with a few microwatts of electrical power consumption. Integration into a silicon ring resonator confirms accurate monitoring of resonant transmission, with enhanced sensitivity of 234 mV/mW at resonance. These results establish a compact, low-power monitor suitable for dense photonic integrated circuits.