Thermal noise and mechanical loss of SiO${}_2$/Ta${}_2$O${}_5$ optical coatings at cryogenic temperatures

Abstract

Mechanical loss of dielectric mirror coatings sets fundamental limits for both gravitational wave detectors and cavity-stabilized optical local oscillators for atomic clocks. Two approaches are used to determine the mechanical loss: ringdown measurements of the coating quality factor and direct measurement of the coating thermal noise. Here we report a systematic study of the mirror thermal noise from room temperature to 4 K by operating reference cavities at these temperatures. The directly measured thermal noise is used to extract the corresponding mechanical loss for SiO${}_2$/Ta${}_2$O${}_5$ coatings, which are compared with previously reported values.

References in corpus (4)

• Exploring the Sensitivity of Next Generation Gravitational Wave Detectors
• An ultrastable silicon cavity in a continuously operating closed-cycle cryostat at 4 K
• A transportable interrogation laser system with an instability of $\mathrm{mod}{\sigma }_{\mathrm{y}}=3\times 10^{-16}$
• Broadband Measurement of Coating Thermal Noise in Rigid Fabry-Perot Cavities

Cited by in corpus (5)

• Excess noise and photo-induced effects in highly reflective crystalline mirror coatings
• A laser with instability reaching $4\times 10^{-17}$ based on a 10-cm-long silicon cavity at sub-5-K temperatures
• Mechanical loss and stability analysis of NEXCERA in ultra-stable optical cavities
• Engineering the sensitivity of macroscopic physical systems to variations in the fine-structure constant
• Cordierite-based optical resonators with extremely low thermal expansion