Evidence of asymmetric beaming in a piecewise-linear propagation channel

Abstract

Asymmetric beaming in a piecewise-linear propagation channel is demonstrated for a single photonic-crystal prism at Gaussian-beam illumination. The used hybrid refraction– diffraction mechanism exploits oblique incidence, the first-negative-order deflection at the longer interface, and asymmetry in coupling at the exit interfaces and does not need blocking of transmission by dispersion in the back ward illumination case. The Floquet–Bloch mode with left-handed behavior and nearly circular equifrequency dis persion contours is utilized. The outgoing waves may have significantly different spatial distributions for the forward and backward illumination cases, yielding asymmetry in the beaming regime.