All-angle polarization-insensitive negative refraction in high-dielectric photonic crystal.

To obtain all-angle polarization-insensitive negative refraction, a 2D square array photonic crystal has been systematically investigated here. The presented structure is composed of air holes in a high-dielectric (ε=36) background and provides all-angle polarization-insensitive negative refraction in the first band along the ΓM direction, in a bandwidth of Δω/ωc=2.4%. The structure is applicable in polarization beam splitters used in integrated space-division multiplexing and has potential applications in highly efficient negative refraction-based phenomena, such as in angle and polarization-independent cloaking and invisibility. The results achieved by the finite difference time domain and the plane wave expansion methods here are in good agreement.