Novel switching of liquid crystals for use in rapid THz phase shifters discovered from the dimensional effects of electrodes

Abstract

Liquid crystal (LC) devices for terahertz (THz) phase shifters have a thick cell gap, which inevitably results in a very slow response, particularly when they rely on the passive relaxation of LCs. To vastly improve the response characteristics of LCs for use in THz phase shifters, we virtually demonstrate a novel type of LC switching in which all processes are governed by an electric field between in-plane and out-of-plane tristable states, resulting in hexadirectional switching with three orthogonal orientation states and thereby attaining a broader range of phase shifts. This type of LC switching is achieved using a pair of substrates that mirror each other, each of which has two pairs of orthogonally arranged fingershaped electrodes for in-plane switching. Further, the two substrates each have one grating-shaped electrode, thus forming a pair of electrodes for out-of-plane switching. Each hexadirectional switching process between the tristable states is driven by an electric field, thus maintaining a rapid response by avoiding long relaxation times.