Graphene/Insulator Stack Based Ultrasensitive Terahertz Sensor With Surface Plasmon Resonance

We proposed a terahertz (THz) surface plasmon resonance (SPR) sensor with Kretschmann coupling configuration with buffer layer covered substrate containing doped monolayer graphene (MLG) directly deposited onto the coupling prism. The performance of the SPR sensor in terms of detection accuracy, sensitivity and figure of merit (FOM) were investigated by applying angular interrogation technique. The results demonstrated that the prism/substrate/graphene coupling structure has higher detection accuracy after coating a low-permittivity buffer layer underneath graphene. Moreover, the sensitivity of sensor could be enhanced using larger refractive index substrate. Furthermore, this proposed structure could effectively overcome the challenge that sample preparation with a small thickness needs to be maintained in Otto geometry based sensor. The results showed the maximum sensitivity of the THz plasmonic sensor up to 49.5 deg/RIU along with a FOM of 8.76 RIU-1. The prominent characteristics of the proposed structure would pave the way for high-performance THz plasmonic sensors.