Active control of terahertz amplitude and phase based on graphene metasurface

Abstract

Metasurfaces with actively tunable features are highly demanded for advanced applications in terahertz (THz) systems. However, realizing dual-tunability is still challenging. In this paper, we demonstrate a dual function modulator based on graphene metasurface. It can actively control the amplitude and phase of THz wave. The unit cell of the device is made up of two T-shaped resonators and a graphene patch between two resonators. By electrically tuning the Fermi level of the graphene patch, the maximum amplitude modulation depth at the central frequency of 0.55 THz can be up to 92%. Meanwhile, the dynamic phase modulation at 0.3 THz can change from −20° to 70°, and the maximum phase difference reaches to 90°. When the incident angle is up to 60°, the amplitude modulation depth is still high than 80%, and the phase difference is more than 70°. Therefore, the device has good performance for incident angles. Our work provides deeper insight into multifunctional integrated THz devices, which will enable a variety of practical applications, such as THz imaging, tunable lens and phase array antenna . • A dual function modulator based graphene metasurface was proposed. • The amplitude and phase of terahertz wave can be actively controlled by changing the Fermi level of graphene. • The modulation depth is high to 92%, and the phase modulation is 90°. • The maximum transmission is 0.7 when the Fermi level is 1 eV.