Terahertz waves and liquid crystals: prospects and challenges

Abstract

Over the last decades, scientists have paid growing attention towards the terahertz properties of liquid crystals. On the one hand, the dielectric properties of liquid crystals are relatively unexplored at terahertz frequencies, and the observed low-energy phenomena are not yet well understood. On the other hand, terahertz technology requires switchable devices, in which liquid crystals could potentially serve as a base material. This paper gives an overview of the research done so far on the properties and applications of liquid crystals in the terahertz frequency range. The path from first liquid-crystal terahertz experiments to comprehensive studies of their structure-property relation is outlined. Furthermore, the evolution from basic concepts to first liquid-crystal terahertz devices is sketched, and prospects as well as future challenges are discussed. Due to the development of compact and cost-efficient components, terahertz spectrometers matured from room-filling laboratory instruments to compact, reliable scientific tools. Modern terahertz systems are thus also covered in this report. Liquid-crystal devices could help terahertz technology continue this trend, and pave the way to a wider range of application.