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

本计画之目的在于发展一个光学积体电路用复合材料组成之三维光波导最佳设计系统。该系统是基于有限元法，它使人们能够精确计算的模式谱的波导组成的非均匀，各向异性，有源，和losses.The最严重的困难，使用有限元分析，非均匀介质波导，是所谓的虚假的，非物理的解决方案的出现。为了克服这个困难，在这个项目中开发了两种改进的方法。一种是罚函数法，另一种是利用横向磁场分量的方法。在前一种方法中，磁场矢量的无发散约束在最小二乘意义上得到满足，并且可以从导波或慢波区域抑制伪解。在后一种方法中，发散关系被隐含地满足，并且在传播图的整个区域中的寄生解被完全消除。首先，对应力作用下的保偏光纤和侧隧道型保偏光纤进行了分析，估算了保偏光纤的模式双折射特性。其次，分析了各向异性介质波导和旋光波导，研究了它们的色散特性。最后，对掩埋异质结半导体激光器进行了分析，并对模式增益特性进行了评价。

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.