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

TL;DR

This study investigates how polarization anisotropy in 3D photonic crystals causes a wavelength-dependent shift in the Brewster angle, affecting light scattering and stop gap behavior with potential applications in nanophotonics.

Contribution

It provides the first detailed analysis of polarization anisotropy effects on Brewster angle shifts and stop gap branching in 3D photonic crystals with face-centered cubic symmetry.

Findings

Brewster angle shifts depend on index contrast and lattice constant.

Stop gap branching occurs at high-symmetry points for TE polarization.

Brewster effect suppresses stop gap branching for TM polarization.

Abstract

The interaction of polarized light with photonic crystals exhibit unique features due to its sub-wavelength 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 wavelength and angular range. 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 strongly depends on the index contrast and lattice constant. Polarization-dependent stop gap measurements are performed on photonic crystals with different index contrast and lattice constants. These measurements indicate unique stop gap branching at high-symmetry points in the Brillouin zone of the photonic crystals. The inherited stop gap branching is observed for TE polarization whereas that is suppressed for TM polarization as a consequence of Brewster effect. Our results have consequences in the polarized light-scattering from plasmonic structures and dielectric meta-surfaces and are also useful in applications like nano-scale polarization splitters and lasers.