Characterization of Optical Microcavity Whispering-Gallery-Mode Resonators

Abstract

In the past decade, optical microcavity whispering-gallery mode (WGM) resonators have received increasing attention for applications in optical communications and nanotechnology. In this paper, the theory for describing radiation transfer and heat transfer in the micro/nanoscale devices is presented first. Then the characteristics of waveguide-microdisk coupling WGM miniature resonators are numerically studied. Focus is placed on the parametric studies over a broad range of resonator configuration parameters including the microcavity size and the gap separating the microdisk and waveguide. The finite element method is used for solving Maxwell’s equations which govern the propagation of electromagnetic field and the radiation energy transport in the micro/nanoscale devices. The EM field and the radiation energy distributions are obtained and compared between the on-resonance and off-resonance cases. A very brilliant ring with strong EM field and high radiation intensity is found inward the periphery of the microdisk under resonances and high energy storage is achieved. The microdisk size affects significantly the resonant frequencies and their intervals. The scattering spectra for three different microcavity sizes are obtained. The gap obviously influences the qualify factor, the full width at half maximum, and the finesse of the resonant modes as well as the capability of energy storage.