SAMOP 2023 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 31: Precision Measurements: Atom Interferometry I (joint session Q/A)
Q 31.7: Talk
Wednesday, March 8, 2023, 12:30–12:45, F102
A thermal noise interferometer for the characterization of optical coatings — •Janis Wöhler1,2, Matteo Carlassara1,2, Firoz Khan1,2, Philip Koch1,2, Johannes Lehmann1,2, Harald Lück2,1, Juliane von Wrangel1,2, and David S. Wu2,1 — 1Max Planck Institute for Gravitational Physics, Hannover — 2Institut für Gravitationsphysik, Leibniz Universität Hannover
The peak sensitivity band of ground-based gravitational wave (GW) detectors are currently limited by a combination of quantum noise and coating thermal noise (CTN). The latter is a result of the intrinsic properties, such as the mechanical loss and Young's modulus, of the high reflective mirror coatings used in GW interferometers. We report on a 10 cm hemispherical Fabry-Perot cavity with suspended mirrors capable of directly measuring CTN on a test mirror. All other noise sources were suppressed below CTN by installing it in the 10m Prototype facility in Hannover to leverage the ultra low noise environment and laser source. The calibration of the interferometer readout was achieved with a photon calibrator. This thermal noise interferometer will be an invaluable tool for characterization as part of the current global research efforts to find suitable new coating materials for future GW detectors.