Leaky Modes in a Multilayer / Rib Waveguide
Application Notes
This application example uses FemSIM to solve for the leaky modes supported by multilayer Gallium Arsenide (GaAs) and (Aluminum Gallium Arsenide) AlGaAs rib waveguide structure. The waveguide consists of multiple AlGaAs layers with varying alloy concentrations on a GaAs substrate, designed to provide optical confinement.
Due to the high substrate index, leakage into the substrate occurs, and the simulation distinguishes between highly lossy substrate radiation modes and the leaky guided modes of interest. Modes are calculated at a wavelength of 1.064 μm using a nonuniform mesh and perfectly matched layer boundary conditions. Both the first and second order TE (Transverse Electric) and TM (Transverse Magnetic) modes are analyzed, with mode polarization identified by the dominant field components.