Crystalline mirrors with minimal thermo-optic noise for space-time metrology

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K03897
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 15020:Experimental studies related to particle-, nuclear-, cosmic ray and astro-physics
• Research Institution: National Astronomical Observatory of Japan
• Principal Investigator: Flaminio Raffaele 国立天文台, 重力波プロジェクト, 特別客員研究員 (10723108)
• Co-Investigator(Kenkyū-buntansha): LEONARDI MATTEO 国立天文台, 重力波プロジェクト, 助教 (90816448)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: gravitational wave / mirror / crystal / coating / thermal noise

Outline of Final Research Achievements

The thermal noise of the mirrors used for the detection of gravitational waves is one of the main limitation to the detector's sensitivity. In this research we investigated mirrors based on GaAs/AlGaAs multi-layers coatings (called AlGaAs mirrors). We evaluated, for the first time, the effect of the thermo-optic noise in mirrors used with small laser beams as the ones used in table-top short optical cavities for the direct measurement of mirror thermal noise. In parallel, we characterized the optical performances of a 2.5 cm diameter AlGaAs mirrors optimized so to minimize its thermo-optic noise. We measured its scattering, its roughness and its point defects. Finally we realized AlGaAs mirrors with 10 cm diameter and we measured their optical performances.

Free Research Field

gravitational wave astronomy

Academic Significance and Societal Importance of the Research Achievements

本研究は、その結果に基づき重力波検出器の感度の向上を図ることができるため、重力波天文学に有用である。さらに、オプトメカニカル研究、レーザー周波数安定化、光時計、垂直外部共振器面発光レーザー、ジャイロレーザーなど、他の科学技術分野への応用も期待される。