Temperature and salinity sensing characteristics of embedded core optical fiber based on surface plasmon resonance

An embedded core fiber sensor based on surface plasmon resonance (SPR) principle is developed. In the structure of optical fiber, the middle of the optical fiber cladding is hollowed out. The hollowed-out part is then filled with a temperature-sensitive layer. For the temperature sensitive layer, polydimethylsiloxane(PDMS) is chosen. A metal layer is placed outside the cladding of the optical fiber to detect changes in the external environment and stimulate the SPR effect.The gold metal(Au) layer is also placed between the cladding and the PDMS to stimulate the SPR effect.The refractive index of seawater varies with salinity and temperature through COMSOL Multiphysics finite element simulation. We can measure the two parameters of salinity and temperature at the same time based on the SPR principle. The sensitivity of salinity and temperature calculated by this sensor is 0.193 nm/%, 0.397 nm/°C. Fiber optic sensors use the SPR principle to detect dynamic, real-time, continuous processes. The measurement range is very wide, and the brightness is also very high.Compared with single-channel measurement of single parameter, this sensor can greatly improve the efficiency of two-parameter measurement. The sensor has the advantages of simple structure, low production cost and high sensitivity, which can realize the simultaneous measurement of two parameters and avoid the crosstalk between parameters. It has great research significance.