Spectral index method applied to the analysis of whispering gallery modes in semiconductor disk resonators

A computationally efficient modelling method is presented that allows for the analysis of the whispering gallery (WG) modes supported by dielectric resonator structures. The approach is based on the spectral index (SI) method that has traditionally been applied to rib waveguides with rectangular cross section. The principle of effective widths is used in order to simplify the problem, producing a method that is simple in its application and so is ideally suited for use in an iterative design environment. The method provides both accurate resonant wavelengths and field profiles that give a practical insight into the behaviour of the structures that is invaluable to the design process. This approach is shown to provide results that are in excellent agreement with those obtained through other more numerically intense methods