Design and fabrication of a TE-pass polarizer based on silicon nitride optical waveguide

An on-chip TE-pass polarizer working near 850nm band is designed and fabricated on silicon nitride platform. The structure is very simple, using a straight silicon nitride waveguide separated from a metal strip by a low index silicon oxide spacer layer. By optimizing the thickness of the spacer layer, the metal strip introduces more loss for TM mode than TE mode. The measured extinction ratio of the fabricated device is around 20dB over a 16nm wavelength range from 837nm to 853nm for a 3mm-long polarizer.