High reflectivity grating waveguide coatings for 1064nm

TL;DR

This paper proposes thin grating waveguide coatings as high-reflectivity, low-thermal-noise alternatives for gravitational wave detector mirrors, demonstrating potential for near-perfect reflectivity with minimal thickness at 1064nm.

Contribution

It introduces a novel design of single-layer grating waveguide coatings optimized for high reflectivity and low thermal noise at 1064nm, based on theoretical analysis.

Findings

Potential for 100% reflectivity with sub-wavelength thickness

Broad spectral response achieved in theoretical models

Suitable for gravitational wave detector test masses

Abstract

We propose thin single-layer grating waveguide structures to be used as high-reflectivity, but low thermal noise, alternative to conventional coatings for gravitational wave detector test mass mirrors. Grating waveguide (GWG) coatings can show a reflectivity of up to 100% with an overall thickness of less than a wavelength. We theoretically investigate GWG coatings for 1064nm based on tantala (Ta2O5) on a Silica substrate focussing on broad spectral response and low thickness.