Development of a new direct frequency comb spectrometer for asymmetric molecules

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K23586
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0402:Nano/micro science, applied condensed matter physics, applied physics and engineering, and related fields
• Research Institution: The University of Electro-Communications
• Principal Investigator: Iwakuni Kana 電気通信大学, レーザー新世代研究センター, 助教 (80837047)
• Project Period (FY): 2019-08-30 – 2021-03-31
• Keywords: デュアルコム分光計 / 分子分光

Outline of Final Research Achievements

Dual-comb spectrometers can observe a broad spectrum with high resolution within short acquisition time, and the next advance of the spectrometer will be spectroscopy in the mid-infrared region where molecular fingerprints exist. However, the sensitivity might be a problem, because of the relatively low dynamic range of mid-infrared detectors. In this work, we are aiming to develop a dual-comb spectrometer taking the advantage of the energy structure of asymmetric top molecules to use the full dynamic range of the detector. We started with the development a polarization maintain fiber-based laser cavity to generate frequency combs having slightly different repetition rates for dual-comb spectroscopy. We also evacuated the frequency comb with stabilizing it to Rb clock and observing absorption of N2O molecules.

Free Research Field

量子エレクトロニクス

Academic Significance and Societal Importance of the Research Achievements

原子に比べ分子は振動・回転の自由度のため、精密分光の対象となる分子種は構造が比較的単純な分子に限られているが、大気化学や医療などの応用に重要な分子は構造が複雑である場合が多い。 スペクトルの複雑さの低減には、吸収強度が大きく、また、単位エネルギーあたりの状態数密度が低い中赤外領域での分光が適す。本研究で開発した光コムはPMファイバーで構成されており、温度や風などがコントロールされていない実験室環境でも有用であることが実証された。