Measurements of radiation pressure effect in cryogenic sapphire dielectric resonators

Abstract

We report observations of the radiation pressure induced expansion of a solid dielectric resonator. This effect causes a fundamental limit to the frequency stability of the resonator. The measurements were made on four high Q-factor quasi-TE “whispering gallery” modes from 9.9 to 12.6 GHz in a monocrystalline sapphire resonator at liquid helium temperatures. The fractional frequency shift is -1.0+/-0.1×10-12 per μJ of energy stored in the resonator. This result is consistent in sign, magnitude, and linearity with the radiation pressure induced lattice expansion term predicted by Braginsky. © 1997 American Physical Society.