Evolution and reflection of ray-like excitations in hyperbolic dispersion media

TL;DR

This paper analytically investigates the formation, propagation, and reflection mechanisms of ray-like excitations in hyperbolic media, revealing unique phase, broadening, and asymmetric reflection properties that enhance understanding beyond previous numerical studies.

Contribution

It provides an analytical description of multimodal ray-like excitations in hyperbolic media, including phase acquisition, broadening, and a novel asymmetric reflection mechanism.

Findings

Rays have Lorentzian profiles and propagate in zig-zag patterns.

Reflection strength is enhanced by destructive interference between modes.

Reflection mechanism is asymmetric, depending on incident direction.

Abstract

Light in hyperbolic dispersion media is known to exhibit an intriguing ray-like character. However, detailed understanding of ray-like excitations in hyperbolic media is surprisingly limited, mostly based on numerical simulations. In our work, we analytically describe the formation of multimodal ray-like excitations in a planar slab of hyperbolic media. We demonstrate that these rays have an approximately Lorentzian profile and that they propagate in a zig-zagged manner. These rays acquire phase in a discrete fashion at every internal reflection inside the slab and broaden at a rate which is proportional to the rate of optical absorption. Moreover, based on this description, we reveal a unique reflection mechnanism where destructive interefernce between the different modes composing the ray can improve the strength of reflection at an interface between a dielectric and a metalic substrate. This reflection mechanism is highly asymmetric, occuring only when the ray is incident from the side of the dielectric substrate to the side of the metallic substrate, and the strength of reflection is shown to be directly related to the width of the ray.