Liquid crystal metamaterial absorber spatial light modulator for THz applications

A terahertz (THz) spatial light modulator implemented with metamaterial absorbers (MMAs) functionalized with isothiocyanate-based liquid crystals (LCs) is experimentally demonstrated. The device is designed to work in reflection mode and is arranged in a 6 × 6 pixel matrix where the response of each pixel is modulated by electronically controlling the orientation of liquid crystal dimers covering the entire metamaterial absorber landscape. Experiments show that each pixel can be controlled independently and that pixelated absorption patterns can be created at will. The SLM shows an overall modulation depth of 75%. Furthermore, computational results show that losses arising from LCs impose a severe limitation on the overall performance and that consequently the modulation depth of each pixel could be improved with liquid crystal mixtures designed primarily for THz frequencies. This work demonstrates the viability of liquid crystal-based reconfigurable metamaterials and highlights their great potential use for future state-of-the-art THz devices. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.