Calculation of thermal noise in grating reflectors

TL;DR

This paper provides a theoretical calculation of thermal noise in grating reflectors, showing potential for significant noise reduction in high-precision measurements like gravitational wave detection.

Contribution

It introduces the first quantitative estimate of thermal noise in grating reflectors and evaluates their advantages for metrological applications.

Findings

Thermal noise can be reduced by up to a factor of ten with grating reflectors.

The noise reduction depends on grating geometry, material, and temperature.

Application to a 3rd generation gravitational wave detector demonstrates practical benefits.

Abstract

Grating reflectors have been repeatedly discussed to improve the noise performance of metrological applications due to the reduction or absence of any coating material. So far, however, no quantitative estimate on the thermal noise of these reflective structures exists. In this work we present a theoretical calculation of a grating reflector's noise. We further apply it to a proposed 3rd generation gravitational wave detector. Depending on the grating geometry, the grating material and the temperature we obtain a thermal noise decrease by up to a factor of ten compared to conventional dielectric mirrors. Thus the use of grating reflectors can substantially improve the noise performance in metrological applications.