All-dielectric polarization-independent optical angular filter

We report on an all-dielectric, polarization-independent angular filter with one-dimension (1D) photonic crystal (PC) composed of semiconductor compatible Si/SiO₂ pairs. The near-symmetric directional band gap of p- and s-polarized components and Fabry-Pérot (F-P) resonances are utilized to realize efficient polarization-independent angular filtering for normal incidence. The proposed angular filter is designed and experimentally demonstrated in a large area (5 cm × 5 cm) with multilayer sputtering depositions. Experimental measurements show that a divergence angle of the polarization-independently transmitted beam through the angular filtering sample at 1550 nm is 2.2° only and the transmission is as high as 0.8 at normal incidence. The proposed and demonstrated angular filter suggests an effective way to design and implement semiconductor compatible, all-dielectric and polarization-independent angular filters in a fashion of simple structure and easy-fabrication, which is expected to have great applications in lighting, beam manipulation, optical coupling and optical communications.