Design of a polarization beam splitter based on periodic waveguide and subwavelength grating

Polarization beam splitters are among the core components for realizing polarization-division multiplexing and polarization control in silicon-based photonic integrated circuits. To address the challenge of simultaneously achieving broadband operation, ultra-compact size, and high extinction ratio in existing polarization beam splitters, we propose a polarization beam splitter composed of a periodic structure waveguide and a gradient subwavelength grating waveguide on a standard 220-nm silicon-on-insulator platform. The transverse electric (TE) output port of the device employs a trapezoidal gradient subwavelength grating waveguide, while the transverse magnetic (TM) output port uses a periodic slotted waveguide. Simulation results show that at the center wavelength of 1550 nm, the insertion loss for TE (TM) is 0.46 dB (0.48 dB), and the extinction ratio is 23.52 dB (16.28 dB). The wavelength range spans from 1482 to 1595 nm (113 nm). The coupling length is only 4.1 μm. The device offers advantages such as a compact structure, large bandwidth, and strong fabrication compatibility, providing an effective solution for high-density silicon-based photonic integration.