Silicon waveguide polarization rotation Bragg grating with chirp, phase shift section or super-structure grating scheme

We describe a Bragg grating with phase shift section, chirp or super-structure grating scheme that converts the input polarization to orthogonal polarization. A very narrow polarization independent wavelength peak can be generated by phase shift structures and multiple diffraction peaks by sampled or super-structure gratings. Polarization independent flat-top response was obtained experimentally by chirped grating.