Characterization of Light Scattering in Microresonator via Symmetry Breaking of Counterpropagating Light

Many applications of microresonators in sensing, telecommunications, designing optical filters [1], generating low-threshold frequency combs [2] and demonstrating spontaneous symmetry breaking (SSB) of light fields [3]–[5] are affected by the losses in microresonators. These losses increase the threshold power for observing nonlinear interactions. While previous works [6] aimed at measuring absorptive losses in microresonators, the other major contribution to the total losses result from scattering induced by sidewall roughness, and the presence of scatterers in the optical path. We study the spatial distribution of scatterers in a microresonator, and determine the directionality and magnitude of the scattered light, thereby obtaining a unique fingerprint of the system.