Characterization of active liquid crystal: comparison using continuous and time domain terahertz techniques

We have fabricated and characterized an active liquid crystal (LC) device operating in the terahertz (THz) frequency range. The device consists of LCs placed between glass plates with electrodes. Liquid crystals (LCs) are good materials for active phase and bias devices. Using both compact continuous wave (CW) and THz time-domain spectroscopy (TDS) system, our experimental results confirmed the phase variation due to mechanical rotation of the LC or to the bias voltage varying from 0 to 30 V applied between the electrodes at different frequencies. This work opens a simple path towards the development of active THz liquid crystal devices to serve as low-cost phase plates.