Polarisation rotation Bragg grating with high diffraction efficiency using Si waveguide top surface groove grating

Polarisation-independent Bragg grating wavelength filter with high diffraction efficiency using silicon waveguide is reported. An antisymmetric grating structure with groove at the top surface of the waveguide is used to generate the polarisation rotation Bragg diffraction. The concept was verified by simulation. Polarisation-independent bandpass filter consisting of 3 dB coupler and polarisation rotation Bragg diffraction was experimentally demonstrated.