High Extinction Ratio and Broadband Silicon TE-Pass Polarizer Using Subwavelength Grating Index Engineering

We propose and experimentally demonstrate a novel approach to implement a low-loss, broadband, and compact transverse electric (TE)-pass polarizer on a silicon-on-insulator platform. The TE-polarizer utilizes a subwavelength grating (SWG) structure to engineer the waveguide equivalent material index. In this paper, the SWG-based polarizer only supports its fundamental TE mode, whereas the transverse magnetic (TM) mode is suppressed under the cutoff condition, i.e., the TM mode leaks from the waveguide with low reflection. The simulations predict that the bandwidth to achieve a polarization extinction ratio (ER) of 35 dB exceeds 200 nm. Experimentally, the measured polarization ER is ~30 dB, and the average insertion loss is 0.4 dB in the wavelength range of 1470-1580 nm. The fabricated TE-polarizer has a compact length of 60 μm.