Switchable terahertz absorber based on metamaterial structure with photosensitive semiconductor

A terahertz absorber based on metamaterial is designed. The tunability of the absorber can be realized by employing photosensitive semiconductor material of GaAs. By adjusting the conductivity of GaAs through photo-excitation, the absorption peak shifts from 2.73 THz to 3.85 THz with full width at half maximum (FWHM) relative to the resonance frequency 4.4% and 21.4% respectively. Qualitative analyses are carried out on the electromagnetic responding modes with different perspectives. Physical mechanisms of the metamaterial absorber are construed with the split-ring resonators model at 2.73 THz and the oscillating conduction model at 3.85 THz. This switchable terahertz absorber owns a great potential in the applications such as optical switch, optical detection, optical coding and others.