Abstract
Tapered couplers between optical fibers, and laser diodes or integrated circuits are very important components for optical communication and optical signal processing. Mode matching at the tapered junction of optical circular waveguide is required to obtain high efficiency and low loss in optical circuits. In this paper, electromagnetic fields in tapered couplers with the inhomogeneous refractive index are investigated for general optical waveguides with arbitrary cross sections. The optimum designs for tapered shape and inhomogeneous refractive index in matching coupler are found by the integral equations using conformal mapping. This method has been developped by the author for the analysis of the complicated millimeter waveguides. Electromagnetic mode conversions and reflections in axial symmetric circular tapered couplers are discussed by integral equations with Green's dyadics and conformall mapping.
