Study on electro-optic noise in crystalline coatings toward future gravitational wave detectors

TL;DR

This study investigates electro-optic noise in AlGaAs crystalline coatings, which are promising for future gravitational wave detectors, and finds the noise level is below current detector sensitivities.

Contribution

It provides the first measurement of electro-optic noise in AlGaAs coatings, demonstrating its insignificance for gravitational wave detection.

Findings

Electro-optic noise in AlGaAs coatings is negligible for current detectors.

AlGaAs coatings have low thermal noise, making them suitable for future upgrades.

The study confirms the stability of AlGaAs coatings against electro-optic fluctuations.

Abstract

Thermal noise in high-reflectivity mirror coatings is a limiting factor in ground-based gravitational wave detectors. Reducing this coating thermal noise improves the sensitivity of detectors and enriches the scientific outcome of observing runs. Crystalline gallium arsenide and aluminum-alloyed gallium arsenide (referred to as AlGaAs) coatings are promising coating candidates for future upgrades of gravitational wave detectors because of their low coating thermal noise. However, AlGaAs-based crystalline coatings may be susceptible to an electro-optic noise induced by fluctuations in an electric field. We investigated the electro-optic effect in an AlGaAs coating by using a Fabry-Perot cavity, and concluded that the noise level is well below the sensitivity of current and planned gravitational-wave detectors.