All-silicon and ultra-compact transverse electric-pass polarizer with large bandwidth and high polarization extinction ratio based on subwavelength metamaterials

Abstract

In this paper, we have proposed an all-silicon and compact transverse electric (TE)-pass polarizer with large bandwidth and high polarization extinction ratio (PER), where the polarizer uses a semi-arc waveguide to cause polarization-dependent bending loss (PDBL). The combination of the subwavelength grating (SWG) and double adiabatic tapers serve as an equivalent cladding to get strengthened PDBL. The parameters of SWG and double adiabatic tapers are analyzed in detail to improve the performance of the device. In the proposed TE-pass polarizer, the injected fundamental TE mode (i.e., TE0) gets protection and the injected fundamental transverse magnetic mode (i.e., TM0) lets out. The footprint is only about 6 μm × 10 μm, which is substantially reduced compared with the previous counterparts. From the results, its bandwidth is as high as 228 nm (from 1.482 to 1.710 μm) with PER > 39 dB and low excess loss (EL < 1 dB), and it has an ultra-high PER of 42.5 dB and a low EL of 0.1 dB at 1.55 μm. In addition, large fabrication tolerances of 20 nm ( ± 10 nm) to the key structural parameters are analyzed.