Design of Three-Dimensional Optical Waveguides Consisting of Composite Materials for Optical Integrated Circuits

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The purpose of this project is to develop an optimum design system of three-dimensional optical waveguides consisting of composite materials for optical integrated circuits. This system is based on the finite-element method which enables one to compute accurately the mode spectrum of a waveguide composed of inhomogeneous, anisotropic, active, and lossy media.The most serious difficulty in using the finite-element analysis, for inhomogeneous dielectric waveguides, is the appearance of the so-called spurious, nonphysical solutions. To overcome this difficulty, two improved approaches were developed in this project. One is the penalty function method and the other is the method using the transverse magnetic-field component. In the former approach, the divergence-free constraint for the magnetic-field vector is satisfied in the least-square sense and the spurious solutions can be supressed from the guided- or slow-wave region. In the latter approach, the divergence relation is implicitly satisfied and the spurious solutions are completely eliminated in the whole region of a propagation diagram.These new approaches were applied for various optical waveguides. First, stress-applied polarization-maintaining optical fiber and side-tunnel type polarization-maintaining optical fiber were analysed and the modal birefringence characteristics were estimated. Next, anisotropic dielectric waveguides and gyrotropic waveguides were analysed and the dispersion characteristics were investigated. Lastly, buried heterostructure diode lasers were analysed and the modal gain characteristics were evaluated.