Polarization-rotating, Bragg-grating filters on silicon-on-insulator strip waveguides using asymmetric periodic...

We report on a wavelength-selective, polarization-rotating filter using a partially etched asymmetric Bragg grating on a compact single-mode, silicon-on-insulator (SOI) strip waveguide. The asymmetric Bragg grating rotates and reflects the fundamental transverse electric (TE) and transverse magnetic (TM) modes at selected wavelengths. Our device offers wavelength-selective, polarization-rotating reflection at its reflection port and wavelength-selective, polarization-independent notch filtering at its through port. The device is fabricated using a CMOS-compatible process with 193 nm-deep ultraviolet lithography on an SOI platform. We present results for a 294.4 μm long device that has a 3 dB bandwidth of 2.63 nm and a low-excess loss of less than 1 dB. This device also has a maximum polarization-extinction-ratio of greater than 27 dB.