Dynamic control of THz polarization modulation and multi-channel beam generation using a programmable metasurface.

Abstract

Polarization modulation and multichannel beam generation are crucial in multichannel communication and high-resolution imaging at THz frequency. In this work, we present a polarization-reprogrammable coding metasurface composed of VO2/Au composite concentric rings (CCRs). Owing to the phase-change property of VO2, the CCR is designed as a digital coding element for the polarization conversion. When VO2 remains insulator state at room temperature, the y-polarized incident wave is transformed into x-polarized wave, which can be regarded as digital state 0. When VO2 converts into metal state at critical temperature (68°C), the polarization of reflected wave stays unchanged, corresponding to digital state 1. Any desired linear polarization state of reflected beam is achieved by taking advantage of different coding sequences in a programmable manner. Furthermore, by combining phase gradient with polarization coding states, we propose an anisotropic programmable metasurface to control the multi-channel reflected beams dynamically. By arranging distinct coding sequences, we show that the EM reflected beams can be manipulated flexibly. The proposed programmable metasurface paves new ways towards THz polarization manipulation, signal detection and information communication.