Unidirectional Light Propagation in Natural Crystals

In recent work, we showed that one-way light propagation, with respect to the incidence angle, can occur in simple, natural crystalline materials, such as crystal quartz, at far-infrared frequencies. Our results support the idea that natural crystals can serve as efficient and functional oriented asymmetric absorbers, features that have led to the use of materials such as the quartz we have studied in developing on-chip devices.