Precision Interferometric Measurement of Mirror Birefringence in High-Finesse Optical Resonators

Published

January 19, 2016

Author(s)

Adam J. Fleisher, David A. Long, Qingnan Liu, Joseph T. Hodges

Abstract

High-finesse optical resonators found in ultrasensitive laser spectrometers utilize supermirrors ideally consisting of isotropic high-reflectivity coatings with power reflectivity $R\geq99.99\%$. Strictly speaking, however, the optical coatings are often non-uniformly stressed during the deposition process and therefore do possess some small amount of birefringence. When physically mounted the cavity mirrors can be additionally stressed in such a way that large optical birefringence is induced. Here we report a direct measurement of optical birefringence in a two-mirror Fabry-P\'{e}rot cavity with $R=99.99\%$ at a wavelength of 4.53 $\mu$m by observing TEM$_{00}$ mode beating during passive cavity decays with noise limited by both quantum and technical sources. We report a splitting of $\delta_{\nu}=618(1)$ Hz, significantly less than the intrinsic cavity linewidth of $\delta_{\text{cav}}\approx3$ kHz. With a cavity free spectral range of 96.9 MHz, the equivalent fractional change in mirror refractive index due to birefringence is therefore $\Δ n/n=6.38(1)\times10^{-6}$.

Citation

Physical Review A

Volume

93

Pub Type

Journals

Download Paper

https://doi.org/10.1103/PhysRevA.93.013833

Citation

Fleisher, A. , Long, D. , Liu, Q. and Hodges, J. (2016), Precision Interferometric Measurement of Mirror Birefringence in High-Finesse Optical Resonators, Physical Review A, [online], https://doi.org/10.1103/PhysRevA.93.013833 (Accessed October 26, 2025)