US Patent 11988870 Bilayer silicon nitride polarization splitter and rotator

A photonic polarization splitter rotator (PSR) includes a substrate, a first optical waveguide disposed on the substrate at a first layer, the first optical waveguide having a substantially rectangular shape and longitudinally arranged between a first end of the first optical waveguide and a second end of the first optical waveguide, and a second optical waveguide arranged to have a partial and fixed amount of overlap over a predetermined length of the first optical waveguide.