Polarization Beam Splitter Based on an Annular Photonic Crystal of Negative Refraction

An annular photonic crystal is used to design a novel kind of polarization beam splitter based on the negative refraction effect. Since TE and TM polarization waves can be excited at the first and second bands, respectively, they will result in different refractive angles and make separation possible. To improve the splitting efficiency, the cut-off treatment along the Γ–M direction and the antireflection coating are introduced to enlarge the separation angle and to decrease the reflection loss. Simulation results show that the proposed polarization beam splitter has a tunable working incident angle that is in the range of 18°–26°. In particular, when the incident angle is 20°, over 90% transmissions can be achieved for both TE and TM polarizations in a wide working frequency range from 0.279(2πc/a) to 0.287(2πc/a).