▎ 摘　　要

We propose a surface plasmon resonance (SPR) based gas sensor in terahertz frequency with Otto configuration based on attenuated total reflection (ATR) technique using free standing doped graphene monolayer. Angular interrogation method has been used to study the performance of the sensor in terms of sensitivity and detection accuracy. Different chemical potential of graphene monolayer has been investigated to study its effect on these performance parameters. The results show that the optimization of the gap distance between the prism base and the graphene monolayer has significant effect on the reflectivity of SPR sensing. This SPR based gas sensor shows ultrahigh sensitivity of 34.11 deg/RIU along with an ultrahigh Figure of Merit (FOM) of more than 1150 RIU-1. (C) 2015 Elsevier B.V. All rights reserved.