Self-referencing refractive index sensor based on graphene-assisted TAMM plasmon cavity resonance

In this Letter, we report TAMM plasmonic polaritons (TPPs) generated by few-layer MoS₂ with a distributed Bragg reflector (DBR) structure in the terahertz frequency region by utilizing the transfer matrix method (TMM) and finite element method (FEM). By inserting a mono-graphene embedded cavity layer, we realize the graphene-induced mode strong coupling (GCM), which is a strategy of a refractive index sensor by optimizing the cavity layer spacing. By adjusting the chemical potential of graphene, GCM is modulated. μ_c = 0.1 eV and μ_c = 0.9 eV are selected as the on-off-state parameters, respectively. The difference in reflectance spectra presents a differential signal and a self-reference operation. The sensitivity of the designed refractive index sensor is 7.8 THz/RIU and a figure of merit (FOM) of 882 RUI^-1 can be obtained. The proposed structure in our Letter demonstrates its potential application in high-performance self-reference refractive index sensors.