Anisotropic-metamaterial-assisted all-silicon polarizer with 415-nm bandwidthPhotonics Research
- Yaocheng Shi, Hongnan Xu, and Daoxin Dai
- received 08/27/2019; accepted 10/17/2019; posted 10/18/2019; Doc. ID 376444
- Abstract: The polarizers have been widely used in various optical systems to reduce the polarization crosstalk. The polarizers based on the silicon nano-wire waveguide can provide chip-scale device size and high polarization extinction ratio. However, the working bandwidth for the on-chip silicon polarizers is always limited (< ~ 100 nm) by the strong waveguide dispersion. In this paper, an on-chip all-silicon polarizer with an extremely broad working bandwidth is proposed and demonstrated. The device is based on an 180o sharp waveguide bend assisted with the anisotropic sub-wavelength grating (SWG) metamaterial cladding. For TE polarization, the effective refractive index for SWG is extraordinary, so the incident TE mode can propagate through the sharp waveguide bend. For TM polarization, the effective refractive index for SWG is ordinary, so the incident TM mode will be coupled into the radiation mode regardless of the wavelength. The fabricated polarizer shows low loss (< 1 dB) and high polarization extinction ratio (> 20 dB) over a > 415 nm bandwidth from 1.26 μm to 1.675 μm, which is at least fourfold better than all the previous works. To the best of our knowledge, such device is the first all-silicon polarizer that covers O-, E-, S-, C-, L- and U-bands.