Graphene-sandwich metasurface as a frequency shifter, switch, and isolator at terahertz frequencies

A graphene-sandwich metasurface for electrically controlled operation as a frequency shifter, a reciprocal switch, and a bidirectional isolator in the terahertz spectral regime was simulated using CST Microwave Studio™ 2019 software. The metasurface is a biperiodic array of identical meta-atoms, each of which comprises a silicon layer with a graphene patch on each of its two faces. The polarization-insensitive metasurface has ∼1/415 dB isolation loss as well as ∼1/415 dB extinction ratio and can be controlled to function over a wide frequency range.