Investigation of Thin-Film Optical Transmission Lines

摘要

Document reports completion of three-year program of theoretical and experimental research on thin film dielectric structures as electromagnetic waveguides at optical frequencies, and guides reader to six publications on results obtained. Analysis was based on an integral equation for electric field in higher-index dielectric region only. Index may be continuous or discrete function of position. A variational method was developed which yields dispersion curves for two dominant modes of infinite cylinder of arbitrary cross section. Numerical results were for rectangular cross section of finite width. Input and output problems for semi-infinite cylinders were given very general unified formulation, embracing single or multimode propagation, neglecting only evanescent modes. Computational difficulties arise in waveguide analysis since kernel of integral equation is singular. Fast, accurate new numerical method to find eigenvalues and eigenfunctions of integral equation with singular kernel was developed, and tested successfully on a one-dimensional model equation having known solutions. An experimental technique for fabrication of thin film dielectric waveguides or optical transmission lines was developed and several experimental lines fabricated and evaluated. Collimated monochromatic visible light was transmitted by these structures under specific conditions. Polarization of transmitted light in plane of structural films was observed. Detection of output, including polarization phenomenon, was by direct observation and conventional measurements, and also by use of silicon planar photodiodes implanted directly in the substrate of the structure. (Author)