Giant light deflection via electro-mechanical modulation of liquid crystals

Abstract

Liquid crystals (LCs) are matter with fluidity and anisotropy and have been used in various electro-optic devices for their capability to modulate the refractive index by voltage. Here, we show that LCs are capable of electro-mechanically modulating light to cause giant light deflection at low voltages (exceeding 64° at 1.0 V). We use a composite material where polymerized cholesteric LC particles that show optical Bragg reflection float in a nematic LC medium. The polymer-particles are elastically coupled with the host director through their surface molecular anchoring and rotate from a face-on to side-on configuration at the Frederik transition. Rigid-body rotation of the reflection plane causes light deflection, which is well reproducible and can be modelled theoretically. Our findings demonstrate the capability of LCs as a micro-electrical-mechanical system platform, which are potentially useful for large-area light-controlling applications.