Six-band continuously tunable terahertz polarization control enabled by liquid crystal-integrated metasurfaces

We experimentally demonstrate a liquid crystal-integrated metasurface that dynamically controls millimeter wave polarization across six distinct frequency bands. Specifically, incident y-polarization electromagnetic waves are converted into x-polarization, left-handed circular polarization, and right-handed circular polarization upon reflection. In our experiments, we characterized the evolution of the polarization states over different frequency bands. The results indicate that as the bias voltage is tuned from 0 V to 4 V: the cross-polarization conversion peaks exhibit a tuning range spanning 270–287 GHz and 383–412 GHz; the LHCP peaks are tunable within 263–269 GHz and 408–476 GHz; the RHCP peaks demonstrate a tuning range of 296–314 GHz and 374–387 GHz. The cross-polarization conversion ratio exceeds 0.95, and the axial ratio is less than 1.9 dB during the modulation process. In frequency bands with overlapping tuning ranges, the bias voltage allows switching among distinct polarization states, including cross-polarization, LHCP, and RHCP. This work provides novel insights into the development of multifunctional integrated millimeter wave devices. The proposed technology holds promise for applications in encrypted THz communication, wireless power transfer, and sensing systems.