Development of a tunable broadband metamaterial absorber based on joint modulation of graphene and photosensitive silicon in the terahertz region

In this paper, a tunable broadband metamaterial absorber based on joint modulation of graphene and photosensitive silicon have been proposed in the terahertz region. While sigma Si = 2000 S/m and Ef = 0.6 eV, the overall bandwidth of over 90% absorption is 0.896 THz and the relative bandwidth is 53%. As is known to all, the conductivity of graphene can be adjusted by bias voltage, and that of photosensitive silicon by optical pumping. So, through regulating the Fermi energy of graphene, central frequency modulation of the broadband absorption can be achieved. By means of laser pumping on photosensitive silicon, we can control the absorption amplitude conveniently. Through joint modulation of Fermi energy and silicon conductivity, manipulation of absorption bandwidth can be obtained. Thus, the absorber can realize active modulation of central frequency, absorption amplitude and absorption bandwidth at the same time. Besides, other influencing factors on absorption performance, such as the polarization angle, the incidence angle, as well as structure parameters are also studied in details. All the simulation results indicate that the proposed absorber possesses fine performance, which could be dynamically modified to fit different application areas.