CMOS-compatible polarizer with tilted polarization angle

A novel CMOS-compatible polarizer with filled polarization angle is proposed and theoretically analyzed. It is the first time, to the best of our knowledge, that an on-chip polarizer with polarization angle other than 0 degrees or 90 degrees is investigated. The polarizer consists of a waveguide, a cladding etched trench and a metal strip. The trench and metal break the symmetry of the waveguide structure and rotate the polarization axes, while the metal also attenuates the specific polarization component. The proposed polarizer is comprehensively investigated from design to fabrication tolerance and 3 different cases with polarization angle 30 degrees, 45 degrees and 60 degrees are demonstrated. The simulated results reveal that extinction ratio as large as 20 dB at 1550 nm can be achieved with excess loss as low as 1 dB, over 100 nm wavelength range. Furthermore, the Monte Carlo analysis shows the feasibility of the proposed polarizer in terms of practical fabrication.