Lossless dielectric tapers with three-dimensional geometry

General properties of two-dimensional tapers for the cylindrical coordinate systems are described. A criterion to determine the index distribution of lossless tapers is given in terms of the phase shift. The design method of lossless tapers with three dimensional geometry is presented. Design equations of tapers for spherical, conical and ellipsoidal coordinate systems are described, and some specific design examples are presented. Tapers for a complicated refractive index can be solved by a numerical method based on the design equations. It is shown that equations for the ellipsoidal coordinates can be reduced to those for coordinate systems with high symmetry.<
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