High-resolution broadband direct comb spectroscopy

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K04930
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 30020:Optical engineering and photon science-related
• Research Institution: Keio University
• Principal Investigator: Hasegawa Taro 慶應義塾大学, 理工学部(矢上), 講師 (80289305)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 光周波数コム / 高分解能分光 / ヘテロダイン分光

Outline of Final Research Achievements

The laser spectroscopy method utilizing an optical frequency comb directly as the light source (hereafter referred to as "direct comb spectroscopy") is a broadband, high-precision, and high-speed infrared spectroscopy technique. In this study, in addition to these features, direct comb spectroscopy with the characteristic of "high resolution" is developed.

To achieve high resolution in direct comb spectroscopy, we developed an optical frequency comb with very narrow mode spacing. On the other hand, for high-speed measurements, optical frequency combs with high repetition frequencies are also required. In this study, a new interleaving method is developed, and a simpler harmonic mode synchronization method to obtain equivalent optical frequency combs has been developed as well.

Free Research Field

レーザー分光学

Academic Significance and Societal Importance of the Research Achievements

本研究では波長分解能が非常に高い赤外線分光法へつながる基本的な手法や光源の開発に成功した。この成果により、従来と比較して高速かつ精密な赤外線分光が可能となる。
赤外線分光は大気中の温室効果ガス(メタンなど)の定量的評価に有用である。本研究の成果を大気中のリモートセンシングに応用すれば、例えば温室効果ガスの密度だけでなく、温度・圧力・同位体比などの網羅的な情報が得られる可能性がある。また、将来においては、詳細な分光情報が未知の他の複雑な分子(フロン・環境ホルモン・カーボンフラーレンなど)の分光情報を網羅的に得ることも可能になる。