A hybrid silicon-sapphire cryogenic Fabry-Perot cavity using hydroxide catalysis bonding

Abstract

The third-generation gravitational wave detectors are under development by operating the detector in cryogenic temperature to reduce the thermal noise. Silicon and sapphire are promising candidate materials for the test masses and suspension elements due to their remarkable mechanical and thermal properties at cryogenic temperature. Here we present the performances of the cryogenic thermal cycling and strength testing on hydroxide catalysis bonding between sapphire and silicon. Our results suggest that although these two materials have very different coefficients of thermal expansion, but if the flatness and the thermally grown $\mathrm{Si}{\mathrm{O}}_2$ oxidation layer on the silicon surface are controlled well, the bonded samples can still survive thermal cycling from room temperature to 5.5 K. A breaking strength of 3.6$\pm 0.6$ MPa is measured for the bonds between sapphire and silicon with a 190 nm silicon oxidation thickness after cooling cycle. We construct a hybrid sapphire-silicon Fabry-Perot cavity with the developing bonding technique in our lab. The measurement results reveal that the cavity can survive repeated thermal cycling while maintaining a good finesse.

References in corpus (12)

• Advanced Virgo: a 2nd generation interferometric gravitational wave detector
• Characterization of the LIGO detectors during their sixth science run
• A sub-40 mHz linewidth laser based on a silicon single-crystal optical cavity
• 1.5 $\mu$m lasers with sub 10 mHz linewidth
• Scientific Objectives of Einstein Telescope
• The Sensitivity of the Advanced LIGO Detectors at the Beginning of Gravitational Wave Astronomy
• Modern Michelson-Morley experiment using cryogenic optical resonators
• The path to the enhanced and advanced LIGO gravitational-wave detectors
• An ultrastable silicon cavity in a continuously operating closed-cycle cryostat at 4 K
• Construction of KAGRA: an Underground Gravitational Wave Observatory
• Thermal noise limited higher-order mode locking of a reference cavity
• Design of an optical reference cavity with low thermal noise and flexible thermal expansion properties