Photoexcited switchable single-/dual-band terahertz metamaterial absorber

A photoexcited switchable single-/dual-band terahertz metamaterial absorber with polarization-insensitive and wide-angle absorption is reported. Through modulating the conductivity of photosensitive silicon embedded in the resonators, the absorber can realize a switching from a dual-band absorption at 0.929 THz and 1.205 THz with 98.88% and 98.70% absorptivity to a redshift single-band absorption at 0.689 THz with 99.29% absorptivity. Meanwhile, it is also found that a switchable single-/dual-band absorption accompanying blueshift and redshift can be achieved by engineering the embedded position of the photosensitive silicon. Furthermore, the extracted electromagnetic parameters, the distributions of the electric fields and the surface currents under different silicon conductivity are demonstrated to give a physical insight into the absorption mechanism. In addition, the proposed absorber possesses polarization-independent and wide-angle absorption for both TE and TM polarization waves.