Effective index-based matrix method for silicon waveguides in SOI platform

Abstract

The work makes an attempt to design and analyze silicon waveguides in silicon on insulator (SOI) platform with the aid of effective index-based matrix method (EIMM). Effective index method is used for wave confinement in depth direction of the waveguides, thus effective indices of the guided modes are computed. A transfer matrix method is applied on the resulted one-dimensional lateral index profile to compute the guided mode propagation constants. Both wire and rib waveguides are designed from its fabrication parameters for single-mode wave propagation at a transmitting wavelength of 1.55μm. Bending losses of bent wires are estimated by a suitable conformal transformation along with EIMM. From our computed results, it is seen that the bending radii exceeding 1μm have negligibly small bending losses. The mode profiles of the silicon wires within the waveguides are also computed for both transverse electric (TE) and transverse magnetic (TM) polarizations. Analysis of some special structures, such as wire waveguide with slanted etched walls, and directional coupler made up of straight and/or curved coupled waveguides are also presented. Some of the computed results of this semi-analytical EIMM are validated with commercially available 2D-FDTD method.