Graphene-based metasurface sensing applications in terahertz band

•We proposed a tunable PIT graphene metasurface, which can realize ultra-high sensitivity terahertz sensor.•The maximum sensitivity and FOM can reach up to 1.7745 THz/RIU and 23.61.•We can find that PIT, reflectivity, and absorbance can be effectively tuned by the Fermi level. Moreover, the FDTD numerical results are well agreement with the CMT results. Ultra-high sensitivity sensor has significant application for micro-nano optical devices in terahertz. Here, we propose a simple graphene metasurface, which can achieve obvious graphene plasmon-induced transparency (PIT) phenomenon. We can find that PIT, reflectivity, and absorbance can be effectively tuned by the Fermi level. Moreover, the finite-different time-domain (FDTD) numerical results are well agreement with the coupled mode theory (CMT) results. Interestingly, an ultra-high sensitivity sensor performance based on tunable PIT in terahertz bands can be realized in our proposed metasurface, the sensitivity and Figure of merit (FOM) can reach up to 1.7745 THz/RIU and 23.61, respectively. Hence, these results can provide theoretical guidance for terahertz dynamic integrated photonic devices.