Direct Observation of Broadband Coating Thermal Noise in a Suspended Interferometer

Abstract

We have directly observed broadband thermal noise in silica/tantala coatings in a high-sensitivity Fabry-Perot interferometer. Our result agrees well with the prediction based on indirect, ring-down measurements of coating mechanical loss, validating that method as a tool for the development of advanced interferometric gravitational-wave detectors.Comment: Final version synchronized with publication in Phys. Lett.