Emergent asymmetries and enhancement in the absorption of natural hyperbolic crystals

The effects of the anisotropy orientation in hyperbolic media have only recently emerged as a way to control and manipulate several optical effects. Here, we show from both experimental and theoretical evidence that highly oriented-asymmetric absorption can be induced in simple crystal quartz. This can be achieved by controlling the orientation of the anisotropy with respect to the surface of the crystal at infrared regions where crystal quartz behaves as a hyperbolic medium. What is perhaps most intriguing here is that not only is the absorption asymmetric, but it can also be significantly enhanced. Finally, we also show various mechanisms through which the asymmetry in the absorption can be optimized, such as controlling the thickness of the crystal. Such phenomena are key for directional-dependent optical devices and present a pathway for engineering angle-encoded detection and sensing

Asymmetric reflection induced in reciprocal hyperbolic materials

Reflection is one of the most fundamental properties of light propagation. The ability to engineer this property can be a powerful tool when constructing a variety of now ubiquitous optical and electronic devices, including one-way mirrors and antennas. Here, we show from both experimental and theoretical evidence that highly asymmetric reflection can be induced in reciprocal hyperbolic materials. This asymmetry stems from the asymmetric cross-polarization conversion between two linearly polarized waves, an intrinsic and more exotic property of hyperbolic media that is bereft of research. In addition to angle-controllable reflection, our findings suggest that optical devices could utilize the polarization of the incident beam, or even the polarization of the output wave, to engineer functionality; additionally, in hyperbolic slabs or films, the asymmetry can be tailored by controlling the thickness of the material. Such phenomena are key for directional-dependent optical and optoelectronic devices