Ultra-compact and low-loss silicon polarization beam splitter using a particle-swarm-optimized counter-tapered coupler

In this paper, an on-chip silicon polarization beam splitter using a particle-swarm-optimized counter-tapered directional coupler is proposed, designed, and fabricated. The coupling length of the proposed device is only 5 µm. As the waveguide width variation ΔW increases from -20 to 20 nm, the simulated polarization extinction ratio larger than 18.67 dB and the corresponding insertion loss lower than 0.17 dB are achieved. Measured experimental results achieved insertion loss <0.50 dB, TE polarization extinction between 16.68 to 31.87 dB, TM polarization extinction between 17.78 to 31.13 dB, over the wavelength range 1525 to 1600 nm.