# Oriented Asymmetric Wave Propagation and Refraction Bending in Hyperbolic Media

## TL;DR

This paper investigates how the orientation of anisotropic hyperbolic media, specifically crystal quartz, affects the propagation and refraction of hyperbolic phonon-polaritons, revealing orientation-dependent phenomena through theory and experiments.

## Contribution

It demonstrates the impact of crystal orientation on hyperbolic polaritons and introduces new effects like asymmetric transmission and surface phonon-polaritons.

## Key findings

- Orientation significantly alters hyperbolic polariton behavior.
- Slight changes in crystal orientation create surface phonon-polaritons.
- Oriented asymmetric transmission of radiation is demonstrated.

## Abstract

Crystal quartz is a well-known anisotropic medium with optically active phonons in the THz region where hyperbolic phonon-polaritons can be excited. Here, we use this material to illustrate how the behavior of bulk and surface hyperbolic polaritons can be drastically modified by changing the orientation of the crystal's anisotropy axis with respect to its surface. We demonstrate, both theoretically and experimentally, phenomena associated with the orientation of hyperbolic media. We show the consequences of slight changes in the crystal's orientation in various ways, from the creation of hyperbolic surface phonon-polaritons to the demonstration of oriented asymmetric transmission of radiation passing through a hyperbolic medium.