High-Performance PCF-SPR Sensor Coated with Ag and Graphene for Humidity Sensing

A highly sensitive photonic crystal fiber (PCF) humidity sensor based on surface plasmon resonance (SPR) is designed and analyzed. A photonic crystal fiber cladding is coated with a silver film and a graphene layer. The outermost layer is coated with agarose gel material to form a moisture-sensitive dielectric layer. The structural parameters, such as the size of the air holes, the starvation thickness of the coating material, and the humidity, are optimized to obtain good sensing performance. Simulation results show that the sensing structure has an average sensitivity of 15.383 nm/%RH for humidity in the range of 10–90%. Compared with the sensor without graphene coating, the sensitivity of the sensor is improved. This sensor with its flexible structure design and high sensitivity can be widely used in the fields of intelligent detection and security monitoring.