Theoretical Analysis of Sensitivity Enhancement by Graphene Usage in Optical Fiber Surface Plasmon Resonance Sensors

Aiming to investigate the graphene usage in optical fiber surface plasmon resonance sensor probes, a theoretical analysis of sensitivity, reflectance, normalized transmitted power, full width at half maximum, and figure of merit (FOM) as a function of the sensing region length for different configurations has been developed. Here, some noble metals, such as gold (Au), silver (Ag), and copper (Cu) have been used as part of the sensing region. Considering aqueous solutions as analytes, the deposition of graphene layers over the metallic layer has improved the performance of the sensor probes. Three graphene-optimized probes have been proposed, one for each metal. When considering water as the surrounding medium, the configuration Cu-graphene-coated probe is the most sensitive, with a sensitivity of 6241 nm/RIU, representing more than two times the sensitivity for a Cu-based probe. On the other hand, the Ag-graphene-coated probe presents the maximum FOM of 75.523 RIU-1. The deposition of graphene layers over the Au-coated probes causes an increase in the sensitivity from 2581 nm/RIU to 4201 nm/RIU.