Terahertz polarization beam splitter based on two photonic crystal cavities

A compact terahertz polarization beam splitter by combining line defects and two photonic crystal cavities is designed and numerically demonstrated. Both plane wave expansion method and finite-difference time-domain method are used to calculate and analyze the characteristics of the proposed device. The simulation results show that the designed polarization beam splitter can split TE and TM polarized terahertz wave into different propagation directions with high efficiency over the terahertz wave frequency range from 1.16 THz to 1.19 THz. The extinction ratios are found to be larger than 20 dB for both TE and TM polarized terahertz wave. By using such a polarization beam splitter, the device size could be reduced significantly. This enables the polarization beam splitter to be used in terahertz wave system and terahertz wave integrated circuit fields.