Comparison of Numerical Studies on Active Rectangular Waveguide Couplers by Vector, Scalar Finite Element, and Effective Refractive Index Methods

Abstract

Three different numerical methods, viz., vector, scalar finite element, and effective refractive index methods, are applied to obtain dispersion relations, modal gains and power distributions in active rectangular waveguide couplers. A cross section of a model for numerical studies is shown in Fig.l. Dimensions are given in the figure. Refractive indices are given in Table 1. Typical values of these constants are chosen for III-V compound semiconductors. It is important to understand characteristics of this type of couplers including active waveguide because this is a basic structure of an optical amplifier or a large cavity laser, etc. So far propagation characteristics of active slab waveguide couplers are analyzed, but due to difficulties to apply conventional methods to rectangular active waveguides, it has not been studied thoroughly yet.