Observation of wavelength-dependent shift in Brewster angle in 3D photonic crystals

Abstract

The interaction of polarized light with photonic crystals exhibits unique features due to its subwavelength nature on the surface and the periodic variation of refractive index in the depth of the crystals. Here, we present a detailed study of polarization anisotropy in light scattering associated with three-dimensional photonic crystals with face centered cubic symmetry over a broad range of wavelength and angle. The polarization anisotropy leads to a shift in the conventional Brewster angle defined for a planar interface with certain refractive index. The observed shift in Brewster angle depends strongly on the index contrast and lattice constant. Polarizationdependent stop gap measurements are performed on photonic crystals with different index contrasts and lattice constants. These measurements indicate unique stop gap branching at highsymmetry points in the Brillouin zone of the photonic crystals. The inherited stop gap branching is observed for TE polarization whereas it is suppressed for TM polarization as a consequence of the Brewster effect. Our results have consequences in the scattering of polarized light from plasmonic structures and dielectric meta-surfaces and are also useful in applications such as nanoscale polarization splitters and lasers.