Switchable metamaterials for broadband absorption and generation of vector beams

Abstract

Metamaterial (MM) based on double-split resonator and vanadium dioxide (VO2) in terahertz (THz) region is proposed in this paper, which integrates broadband absorption (ABS) and generation of vector beams. Simulation results show that by tuning the VO2 into metallic phase, the ABS of proposed MMs achieves over 90% in 1.35–2.18 THz. The physical mechanism of broadband ABS is clarified by introducing the impedance matching theory and distributions of electric field. Moreover, ABS characteristics of the designed MMs at different polarization angles and incident angles are also studied, respectively. While VO2 is in insulated state, simulation results indicate that the radial polarized beam and the angular polarized beam can be generated when the incident wave is x-polarization and y-polarization, respectively. The polarization conversion rate over 90% is realized between 1.37 THz and 2.20 THz within the incident angle of 10°. The bi-functional MMs proposed in this paper has promising applications in modulators, imaging and sensors.