Study on the polarization-insensitive self-collimation behavior in two-dimensional all-solid photonic crystals

Abstract

Due to unavoidable separation of bands for different polarizations, it is usually difficult to realize polarization-insensitive self-collimation (PISC) from conventional rod-type two-dimensional photonic crystals (PCs). In this paper, we have systematically investigated the band, equi-frequency contours, and transmission properties of a special two-dimensional PC that quite resembles the structure of conventional rod-type PCs. By only replacing the air background in rod-type PCs with dielectric background, the so-called all-solid two-dimensional PC can show much closer bands than conventional rod-type PCs. Such suppressed band feature is quite beneficial to the formation of flat equi-frequency contours for both polarizations at the same frequency, namely a PISC effect. By further comparing the PISC in different all-solid PCs and optimizing the cut-off value at PC terminations, we have obtained some useful rules to control the performance of PISC. Finally, based on the special PISC effect in all-solid PCs, we have also given two specific examples to illustrate the potential ability of all-solid PCs in realizing novel polarization-insensitive functional devices.