Silicon-based subwavelength grating polarization beam splitter with asymmetric directional coupler

In this paper, a novel polarization beam splitter (PBS) is proposed. The silicon-based subwavelength grating (SWG) is successfully applied to the asymmetric directional coupled PBS, and the research shows that its performance has improved in many aspects. By carefully optimizing structural parameters, the transverse electric (TE) polarization is in a reflected state in the SWG, which effectively weakens the coupling strength, while the transverse magnetic (TM) polarization is almost unaffected. Simulation results show that the bandwidths of TE polarization and TM polarization are 200 nm (1450-1650 nm) and 141 nm (1450-1650 nm) in the extinction ratio of >20 dB, respectively, while the insertion loss is <0.5 dB and <1.3 dB, respectively. The PBS is very robust to the process production. With the manufacturing error exceeding 20 nm, the performance is only reduced by 0.6 dB, effectively solving the problem of complex preparation process.