GaAs-enabled tunable multifunctional devices based on three coupling mechanisms for terahertz metamaterials

Abstract

In this paper, a terahertz metamaterial structure with multiple physical features such as EIT-like resonance, Fano resonance, and terahertz wave absorption, is implemented. The device consists of a metal structure and a GaAs layer. The conductivity of GaAs can be adjusted by optical pump. When the conductivity of GaAs is 10 S/m, with the TE polarization wave incenting, the Fano resonance formed, and when the TM polarization wave was incenting, the EIT-like resonance formed. Modulation of the resonance can be achieved by adjusting the conductivity of GaAs, and a maximum modulation depth of 96.5% is obtained. When the conductivity of GaAs is 2 × 105 S/m, a double narrow-band absorption is obtained with TM polarization wave exciting. The maximum sensitivity reaches 513 GHz/RIU and the maximum FOM value reaches 39.5, which indicates that the device has excellent performance in refractive index sensing. The device also has a wide range of applications in terahertz sensors, slow-light devices, and terahertz modulators.