We present an optically controlled terahertz (THz) switch to tune the state of polarization based on single-layer chiral metamaterial. The chiral metamaterial consists of an array of perforated S-shaped slits with incorporated photoactive silicon, which allows us to control dynamically cross-polarization transmission. The switch state can be efficiently controlled by external optical stimuli. The realization of cross-polarization THz switch in a single-layer metamaterial has simple structure design and easy fabrication and therefore the S-shaped metamaterial will be a promising candidate for polarization control devices.
We demonstrate selective coherent perfect absorption based on interaction between bilayered asymmetrically split rings (ASRs) metamaterials and a standing wave formed by two coherent counter propagating beams. The selective coherent perfect absorbers with high absorption have been achieved depending on the phase difference between two coherent beams. The selective coherent control absorbers can be well designed by changing the thickness of the dielectric layer and the asymmetry of the ASRs. The coherently controlled metamaterials provide an opportunity to realize selective multiband absorption and ultrafast information processing.
We propose an ultrathin planar metamaterial with an abrupt phase change along its surface for beam manipulation. The metamaterial is composed of bilayered asymmetrical split ring apertures (ASRAs) on either side of a dielectric substrate. The proposed metamaterial relies on eight variable ASRAs in a super cell to modulate the phase of transmitted wave. Efficient beam direction manipulation for cross-polarization transmission has been achieved and co-polarization transmission has been completely suppressed. Numerical simulation results show that the linearly polarized incident wave can deflect in a designated direction passing through the ultrathin metamaterial. An intensity efficiency of 70% and a deflection angle of 24° at 6.2GHz have been verified.