Graphene based surface plasmon resonance gas sensor with magnetic field control for Terahertz

Abstract

In this paper, a surface plasmon resonance (SPR) based gas sensor using a modified Otto coupling configuration, which is a sandwich structure including high refractive index prism, dielectric layer, graphene monolayer and gas analyte, was investigated. Different from the already reported Otto SPR gas sensor, the proposed gas sensor introduces an active magnetic field control and one dielectric layer between Germanium prism and a graphene monolayer. The effect of the key system parameters such as the thickness, refractive indices of the dielectric layer, magnetic field, sensitivity on the performance of the sensor is analyzed through angular change via Transfer matrix method. It was shown that when the thickness and refractive index of dielectric layer is chosen as 12 μm, 1.5 respectively, the effect of attenuated total reflection (ATR) is optimal at the operating frequency of 5 THz. The results also show the sensitivity of the sensor will increase with an increase in analyte refractive index at the same magnetic field intensity. In addition, the sensitivity also increases with the magnetic field intensity, such as from 38 to 941 deg/RIU_1 in the range of 0 to 1 T magnetic field intensity for the analyte refractive index n a = 1.0001. Thus the proposed sensor with high sensitivity provides a new platform for gaseous sensing at THz frequency.