Broadband tunable absorber for terahertz waves based on isotropic silicon metasurfaces

A broadband tunable absorber is studied based on the silicon metasurface at terahertz frequencies. By tuning the conductivity of silicon, absorptance is more than 90% from 0.497 THz to 1.045 THz with central frequency of 0.771 THz when the conductivity is equal to 2500S/m. Simulated results show that absorptance peak can be modulated from 1% to 100% when the conductivity continuously changes from 0S/m to2500S/m. The central-symmetry structure leads to polarization independence. Our design may be used as optoelectronic modulator, tunable detector, and terahertz switch.