Metamaterial nonlinear and polarization-dependent bi-frequency THz switch

In this work, we propose a novel metamaterial structure with two concentric split-ring resonators. The splits are filled by photoconductive Si. Illuminating the structure using an oblique optical pump with a wavelength of 800 nm, in addition to the normal THz signal wave, excites the structure by varying the Si conductivity. Also, by changing the direction of the incident TE wave by 90°, the transmission frequency is changed. Therefore, the structure operates as a switch at two different windows using two different methods. The response time of the photoconductive switch is less than 3 ps. The substrate was replaced by a more cost-effective and flexible material, polyimide, to achieve even more exciting results in broadening the switching windows. Also, the response time of this switch is less than 1 ps. Finally, for verification of the simulation results, a circuit model of the photoconductive switch is proposed, and the results comply very well with the simulation results. The proposed switch can be used in fast optical systems and networks.