Calculation of Radiative Loss in Index Contrast of AlxGa1-xAs Waveguides

Abstract

Abstracts In this paper we used a theoretical and numerical investigation model to calculate the radiation losses, penetration depth and effective indices for Al x Ga 1-x As planar optical waveguides at a wavelength of 1550 nm. Newton-Raphson method was used to find the radiation modes and its wavenumber. It was found that the change in the refractive index of Al x Ga 1-x As optical waveguide is responsible of scattering effects and radiation towards the substrate. Keywords: Radiation, Loss, Optical planar waveguides, refractive index. Introduction Due to the limited control in waveguide fabrication the radiation losses naturally occur in most materials, and the energy does not remain in the core [1]. Lots of energy can flow either through the substrate or cladding region. One of reasons is due to physical discontinuities of the dielectric waveguide cause guided energy loss by radiation [2, 3] . Losses usually arise due to radiative scattering into the surrounding material and into backward-propagating modes due to the change in the refractive index of the core [4, 5]. There are several methods to calculate radiation modes such as the Fourier decomposition method (FDM), Perturbation calculus (PC) and the spectral decomposition method (SDM) [6, 7]. In this paper, we present a numerical model that gives insight into the physical processes involved in waveguide losses and which permits us to derive design guidelines for low-loss optical waveguides Al