Photoinduced dynamically tunable terahertz metamaterial absorber

Abstract

A photoexcited switchable single-band/dual-band terahertz metamaterial absorber with polarization-insensitive and wide-angle absorption is reported. The function switching is realized by modulating the conductivity of the photosensitive GaAs embedded in the resonator, and the surface currents at different GaAs conductivities are extracted to physically explain the absorption mechanism of the metamaterial absorber. The results show that the absorber can realize switching from dual-band absorption at 0.568 and 1.442 THz with 99.08% and 99.56% absorptivity, respectively, to a shift single-band absorption at 0.731 THz with 95.43% absorptivity. The device has an intensity modulation depth of 61.4% and a frequency tuning bandwidth of 60.6%. With these values, the device can be used to fabricate intensity modulators and frequency-selective absorbers in the terahertz band. In addition, the proposed absorber exhibits polarization-independent and wide-angle absorption for transverse electric(TE)and transverse magnetic(TM)polarization waves. The realization of tunable metamaterial absorbers offers opportunities for mature semiconductor technologies and potential applications in active terahertz modulators and switchers.

Keywords

terahertz / metamaterial absorber / photoexcitation / dynamically tunable