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arXiv · 1609.05595

Audio-band Coating Thermal Noise Measurement for Advanced LIGO with a Multi-mode Optical Resonator

S. Gras·H. Yu·W. Yam·D. Martynov·M. Evans
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Abstract

In modern high precision optical instruments, such as in gravitational wave detectors or frequency references, thermally induced fluctuations in the reflective coatings can be a limiting noise source. This noise, known as coating thermal noise, can be reduced by choosing materials with low mechanical loss. Examination of new materials becomes a necessity in order to further minimize the coating thermal noise and thus improve sensitivity of next generation instruments. We present a novel approach to directly measure coating thermal noise using a high finesse folded cavity in which multiple Hermite-Gaussian modes co-resonate. This method is used to probe surface fluctuations on the order 10^-17 m\rtHz in the frequency range 30-400 Hz. We applied this technique to measure thermal noise and loss angle of the coating used in Advanced LIGO.

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S. Gras, H. Yu, W. Yam, D. Martynov, M. Evans. 2016-09-19. Audio-band Coating Thermal Noise Measurement for Advanced LIGO with a Multi-mode Optical Resonator. https://doi.org/10.1103/physrevd.95.022001

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