Phase noise transfer in resonant optical cavities

Abstract

We study theoretically and experimentally the field circulating in a resonant optical cavity when the phase of the incident field and the length of the cavity exhibit fluctuations about their mean values. With a simple model we derive transfer functions which relate the spectral density of phase noise of both the input field and the cavity length to that of the circulating field. In agreement with the standard steady state result, we find that phase noise in the incident field is low pass filtered by the cavity. Cavity length fluctuations are found to be high pass filtered in their transfer to the circulating field. These results are used to present a control loop model of the cavity-laser system. We verify the model experimentally with a Pound–Drever–Hall discriminator and apply it to a discussion of the stability of a frequency reference at 532 nm.