Full-wave simulation of optical waveguides via truncation in the method of moments using PML absorbing boundary...

Full-wave simulations of optical waveguides are often intractable due to their large electrical size. Naively focussing on a smaller part of the waveguide, e.g. to study coupling, offers no solution given the non-negligible interaction with the remaining parts of the structure. Thereto, in this paper, the coordinate stretching formulation of a perfectly matched layer is integrated into a method of moments based boundary integral equation solver in order to damp the interaction between multiple parts, allowing to focus on the part of interest. The new technique is validated using the classical example of scattering by a wedge. By truncation of the simulation domain to merely ten wavelengths from the tip, the advocated method is found to be both efficient and accurate compared to a traditional, analytical solution technique. Next, the method is applied to model a silicon polarization beam splitter excited by a Gaussian beam.