Polarization-Insensitive Silicon Nitride Photonic Receiver at 1 μm for Optical Interconnects

This paper demonstrates with FDTD simulations a silicon nitride polarization independent coarse wavelength division multiplexing (CWDM) receiver platform based on square waveguides for optical interconnects at 1 μm. Here, the channel spacing of the demultiplexers is much smaller than standard CWDM systems (25 nm) and is set to 8 nm. To avoid high waveguide propagation and radiation losses, several waveguide dimensions were considered. The 450 nm (width) x 450 nm (height) waveguide presented a good tradeoff between low loss and single-mode behavior and was therefore selected. The demultiplexer has a simulated polarization dependence on the waveguide's width variations of 0.17 nm/nm. In addition, we present edge coupler designs with coupling loss within 2.5 dB for TE and TM polarization.