High-Efficiency and Tunable Terahertz Linear-to-Circular Polarization Converters Based on All-Dielectric Metasurfaces

Terahertz polarization converter has drawn great attention for its properties of wavefront control in recent years. However, the low transmission efficiency of these converters remains a major obstruction to be resolved. A promising solution is the all-dielectric metasurface, based on which, this study proposes a high-efficiency transmissive terahertz linear-to-circular polarization converter. The simulations show the transmission efficiency of the converter is beyond 88% with an ellipticity < −0.8 from 0.555 to 0.737 THz, and the maximum efficiency even reaches 100% at 0.660 THz. Furthermore, the converter can also be actively manipulated by combining with dynamic material. The frequency sensitivity is 98 GHz/100K, and the modulation depth of ellipticity at 0.725 THz exceeds 76%. The excellent performances of these converters offer more potentials for terahertz devices.