All-Silicon Terahertz Metasurface With Sharp Fano Resonance and Its Sensing Applications

The all silicon terahertz metasurface with sharp Fano resonance and its sensing applications with high Q factor have been investigated. Such metasurface, composed of periodic grooves, can be fabricated by deep silicon etching on high-resistivity silicon. When the refractive index of the sample changes, the shifted resonance frequency appears and the resonance intensity can be modulated by altering the surface conductivity. The Q characteristics of the metasurface and the applications of graphene sensing are then analyzed and verified. The results indicates that the Q factor of the metasurface can reach 39857, the standard sensitivity is 16042 nm/RIU, and the FOM is 533. Meanwhile, the characteristics of sensing graphene samples (∼1 nm) are very useful for sensing other ultra-thin materials or biomolecules.