Intervalley Scattering Induced Terahertz Field Enhancement in Graphene Metasurface.

Terahertz (THz) field enhancement has significant applications in high-resolution imaging, next-generation wireless communications, and networking. In this work, we experimentally demonstrate a graphene metasurface for THz field enhancement that is based on the intervalley scattering theory. Each meta-atom of the metasurface is composed of one split-ring resonator (SRR) embedded in one graphene patch. The experimental results show that, by electrically adjusting the conductivity of the graphene patch, the THz field through the entire sample is enhanced by 23 times and the transmission amplitude at 0.47 THz decreases 8.4 dB. Moreover, the maximum phase difference at 0.43 THz reaches 88°. The experiment shows good agreement with simulation. This study paves a way for exploring THz-matter interactions and nonlinear optics.