EVANESCENT-WAVE COUPLING OF WHISPERING-GALLERY MODES OF A DIELECTRIC CYLINDER

By developing a direct correspondence between a given whispering gallery mode of a dielectric cylinder and a mode of an equivalent waveguide ring resonator, the evanescent wave coupling characteristics of such modes can be simply modelled. This also allows the conditions for resonant excitation of a single whispering gallery mode to be determined. The model needs a coupled mode theory which accurately describes the coupling between a straight waveguide and a curved waveguide to be developed. This theory is checked against BPM results.