Particle swarm optimized polarization beam splitter using metasurface-assisted silicon nitride Y-junction for mid-infrared wavelengths

摘要

A polarization beam splitter based on metasurface-assisted silicon nitride Y-junction for mid-infrared wave-lengths is proposed and numerically investigated. By properly selecting the structural parameters using the finite difference time domain method and particle swarm optimization algorithm, the input fundamental transverse-magnetic (TM0) and transverse-electric (TE0) modes can be converted and separated from each other with high efficiency. Simulation results exhibit that the conversion efficiencies for TM0-to-TE1 polarization and TE0-to-TM0 polarization are respectively 97.4% and 97.6%. At the mid-infrared wavelength of 2. 5 mu m, the polarization extinction ratios of the designed PBS with the input TM0 and TE0 modes are 27.45 and 27.61 dB. The corresponding insertion losses are 0.21 and 0.31 dB. Within a bandwidth from 2. 45 mu m to 2.55 mu m, the polarization extinction ratio is greater than 19.48 dB and the insertion loss is less than 1.41 dB.