MODELLING OF GALLIUM(X)INDIUM(1-X) ARSENIDE (Y)PHOSPHORUS(1-Y) ELECTROOPTIC MODULATORS AND DIRECTIONAL COUPLERS.

摘要

The propagation of optical radiation in anisotropic rectangular thin film structures with finite conductivities in every region of the guiding structure has been established. The wave-equation is solved for the diagonal tensor waveguiding medium by employing approximate eigenfunctions, and the resulting eigenvalue equations have been perturbed to include complex refractive indices. A step-wise iterative numerical algorithm is devised and used to solve for the modal characteristics. In addition, the coupling of an incident elliptically Gaussian beam on the biaxial thin film waveguide is represented.;Optical directional coupling can be obtained when an array of these ribs are properly spaced, such that signal switching from one guide to another is achieved. Computed coupling characteristics for an adjacent waveguiding pair are given.;The modelled devices are compatible with the existing heterostructure quaternary laser diodes, and thus they have potential for the realization of high data rate integrated optical communication circuits.;Using this model, computer simulation is performed for optical waveguiding ((lamda)(,op) = 1.27 (mu)m) in the p('+)-n('-)-n('+) and pseudo-Schottky rib semiconducter heterostructures of a square cross-section where, in each case, the waveguiding n('-)-layer is taken as the Ga(,x)In(,1-x)As(,y)P(,1-y) material system. For reverse-biased operation of these devices, the junction electric field induces perturbations in the dielectric coefficient of the depletion region via the electrooptic effect and thus modulation of the guided optical carrier is achieved by applying a time-varying signal. Results are presented for intensity and phase shift modulations.