Optical resonances in rotating dielectric microcavities of deformed shape

We investigate numerically rotation-induced changes of optical resonances in wavelength-scale dielectric cavities that are deformed from a circle. The relative change in the quality factor due to rotation is usually larger than that of the resonant frequency, even though both exhibit a threshold behavior, i.e., they barely change at low rotation speed. This threshold is increased at large deformation, which lowers the sensitivity to rotation. Presence of wave chaos can further increase the threshold for rotation-induced changes in resonant frequencies. Unlike the resonant frequency and quality factor, the change in far-field emission pattern by rotation does not display a threshold behavior, thus having a higher sensitivity at low rotation speed. The threshold behavior can be eliminated by designing the cavity shape with special symmetry, and the response of the far-field emission to rotation is also enhanced.