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. •A switchable metamaterial terahertz absorber is proposed. The simulations show that perfect absorption can be achieved by the designed narrow-band terahertz absorber, which may find applications in photoelectric detection, bio-sensing, narrow band thermal radiation. A switchable metamaterial terahertz absorber is proposed. The simulations show that perfect absorption can be achieved by the designed narrow-band terahertz absorber, which may find applications in photoelectric detection, bio-sensing, narrow band thermal radiation.•The tunability of the absorber can be realized by photo-excitation on the photosensitive semiconductor material of GaAs in the proposed structure, which is comparatively simple in manufacture and mode switching operation.•The theory includes the split-ring resonators model and the oscillating conduction model in accordance with simulation results are devised to explain different electromagnetic response of the designed metamaterial, which can be used for instruction of achieving desired absorption characteristics.