Tunable and reflective polarization converter based on single-layer vanadium dioxide-integrated metasurface in terahertz region

A single-layer and actively tunable reflective polarization converter is proposed, which is composed of periodical two-dimensional unit cell of inclined split circular ring filled into by vanadium oxide (VO2) and central rod. Through numerical simulation obtained by the CST Microwave Studio, we find that the broad bandwidth of reflective cross-polarization conversion above 90% is normally obtained from 2.03 to 5 THz at the temperature about 25 °C for both the linearly and circularly polarized wave incidence. At the same time, the polarization conversion ratio (PCR) and energy conversion ratio (ECR) have been furtherly investigated, which reflect high cross-polarization conversion efficiency with nearly no energy loss at room temperature of 25 °C. Thereafter, namely, the cross-polarization conversion can be achieved by theoretical analysis from the views on qualitative variables of polarization azimuth angle (θ), ellipticity (η) and symmetrical polarization decomposition. What is more, the device is sensitive to the incident angles which result into the split reflected frequency spectrum. Afterwards, the actively dynamic responses for reflective frequency spectrum depending on the insulator-to-metal phase transition of VO2 have been investigated. To be demonstrated, the physical mechanism of changeable polarization conversion has been discussed by the distributions of current densities. Lastly, also, the influences of structural parameter variation can be further studied. According to the interesting results, the method provides a strategy that manipulate active and passive metadevices for polarization converter, wireless communication in THz wavelength domain.