High-speed processing of low-loss optical waveguides by controlling the distribution of electron excitation using spatial light modulation

2023 Fiscal Year Final Research Report

• Project/Area Number: 22K20399
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0301:Mechanics of materials, production engineering, design engineering, fluid engineering, thermal engineering, mechanical dynamics, robotics, aerospace engineering, marine and maritime engineering, and related fields
• Research Institution: The University of Tokyo
• Principal Investigator: Reina Yoshizaki 東京大学, 大学院工学系研究科(工学部), 助教 (80967852)
• Project Period (FY): 2022-08-31 – 2024-03-31
• Keywords: 超短パルスレーザ / 光導波路 / 内部改質 / 屈折率計測 / 電子励起 / その場観察

Outline of Final Research Achievements

The inscribing of modifications in transparent materials using ultrafast pulse lasers is a crucial technique for the fabrication of photonic integrated circuits. However, the process of modification inscription is complex, and efficient writing of low-loss optical waveguides has not yet been achieved. This study aims to clarify the modification inscription process in transparent materials via ultrafast pulse laser irradiation to achieve spatial control and efficient writing of low-loss optical waveguides. By employing a newly developed quantitative evaluation method, we successfully measured the process of energy absorption and refractive index change within the optical waveguides. Based on the insights obtained, we achieved the inscription of waveguides in α-quartz at a speed over 20 times faster than previous studies, at 1.5 mm/s, with a propagation loss of 5 dB/cm.

Free Research Field

微細加工

Academic Significance and Societal Importance of the Research Achievements

本研究は，透明結晶材料における超短パルスレーザによるTypeⅡ型の光導波路書き込み過程を定量的に明らかにした．従来研究によって高効率かつ低損失な光導波路書き込みのためにパラメータの最適化が行われてきているが，そのパラメータで光導波路がどのように形成されるかは十分に明らかになっていなかった．本研究は加工パラメータが直接関与するミクロな視点の加工現象とマクロな視点の光導波路の性能の関係を紐解いた．加工パラメータがどのように光導波路形成に影響するかという知見は，今回研究対象にしたα水晶だけでなく，他のレーザ媒質やダイヤモンドに対する光導波路形成にも応用可能であり，産業応用への展開が期待される．