COUPLING CHARACTERISTICS OF NONPARALLEL DIELECTRIC WAVE-GUIDES

A coupled mode equation for two nonparallel dielectric waveguides is rigorously derived from the Lorentz reciprocity theorem. The waveguides are located close to each other. Two local coordinate systems are introduced to present an intrinsic mode function. A global coordinator system also is employed to solve the coupled mode equation. As a numerical example, a coupling system consisting of two dielectric disks with different radii is analyzed. The coupled mode equation for whispering gallery modes propagating along a circumference of the disks is solved numerically in the global coordinate system. Eigenvalues of the whispering gallery modes are complex numbers because of radiation and dielectric losses. As a result, electric field distribution and the coupling coefficient around the coupling system are obtained quantitatively.