Optical confinement study of different semi conductor rib waveguides using higher order compact finite difference method

Abstract

Semi conductor optical wave guides with well defined refractive index profile and geometric shapes which help to understand the propagation properties are widely used in the field of integrated optics. Accordingly rib waveguides are considered, as this structure allows the greatest versatility in device design in which the basic concept employed is its compositional changes in the vertical direction where the three regions of the rib structure are divided into zones with specific refractive indices. As for these types of structures no precise analytic solution is obtained, different numerical techniques have been implemented for their study in terms of their modal analysis. So an accurate higher order compact (HOC) finite difference method (FDM) in combination with conjugate gradient method (CGM) is used here for the investigation of refractive index profile of GaAs and GeSi rib waveguide structure to show their effect on transmission properties of the guided wave using Helmholtz wave equation. The difference in surface and contour plots of the polarized E-field solution clearly shows the material dependence of transmitted waves. We have also studied the variation of optical confinement factor with a number of parameters to understand the propagation properties appropriately as per the requirement of various guided wave optoelectronic devices.