Abstract

Cylindrical or spherical dielectric-cavity resonators in which high-Q modes are created by total internal reflection of electromagnetic waves circulating around the perimeter are commonly used as components in lasers and in sensitive detectors. The spectral properties of such resonators are crucial to the functioning of microdisk lasers¹ and to the nonlinear optics of liquid droplets.² An ideal resonator of this type consists of a dielectric body of perfect axial or spherical symmetry that totally internally reflects the light traveling in whispering- gallery modes almost tangential to the boundary. In an ideal resonator the light in these modes will escape only by evanescent leakage; thus they have very high Q (>10⁸) and emit light isotropically (which can be a disadvantage in certain applications.² In this work we study the effect on these high-Q modes of substantial deformations from rotational symmetry (1%-20%) by using a ray-optics model and concepts from classical nonlinear dynamics.³'⁴ Because the model is based on ray optics, it describes cavities whose typical dimensions are large compared to the wavelength and the smooth deformations.

© 1995 Optical Society of America