Liquid-crystal-enabled electrically tunable terahertz achromatic-wave plate

A THz achromatic quarter-wave plate (AQWP) based on liquid-crystal (LC) phase shifters which have different thickness and orientations, respectively, has been designed and demonstrated. Electrical properties for LC cells is taken into account as well to be used to compensate the thickness of the cell and to accomplish the aim of achromatic tunability. Indium-tin-oxide nanowhiskers which show outstanding THz transmittance are employed as the transparent electrodes in AQWP. The performance of the AQWP analyzed by Stokes parameters have shown the achromatic ability in the frequency range of 0.2~0.8 THz, and can be electrically tuned to 0.3~0.9 THz.