Proposal for a Polarization-Insensitive and Fabrication-Tolerant CWDM (de)Multiplexer Based on Cascaded Silicon Nitride Mach-Zehnder Interferometers

We propose a polarization-insensitive coarse wavelength division multiplexing (de)multiplexer with large fabrication-tolerance. This device uses a two-stage-MZI coupler with multi-mode waveguide to reduce the phase error, and a two-sections phase-shifter for polarization dependent dispersion engineering. Simulation results show low polarization dependent losses (<0.05dB) within a fabrication-error range of 30 nm.