Liquid-crystal-based magnetically tunable terahertz achromatic quarter-wave plate.

Development of the wideband and tunable quasi-optic terahertz (THz) components is in high demand. In this work, we demonstrate a tunable achromatic quarter-wave plate (AQWP) for the THz frequency range. The phase retardation of this device can be set at 90° ± 9° from 0.