Implementation of a Paraxial Optical Propagation Method for Large Photonic Devices

While Comsol Multiphysics has great flexibility for modeling photonic devices, the computational demands of the general finite element method make it most suitable for small devices, on the order of a few microns in extent. Many integrated optical devices are much larger, having lengths of hundreds of microns or millimeters. A beam propagation method (BPM), which applies some simplifying assumptions that enable the use of a coarser grid or mesh, is commonly used to simulate larger devices. In this paper we present an implementation of a BPM-like method in Comsol Multiphysics and demonstrate its application to several common photonic devices.