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

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 investigates 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 cutoff 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.Accepted versio