SPR and FBG sensors system combination for salinity monitoring: A feasibility test

This paper presents a novel optical fiber sensor system for salinity monitoring using data fusion in different optical fiber sensors approaches. In this case, a surface Plasmon resonance (SPR) sensor in a D-shaped optical fiber is developed in conjunction with a fiber Bragg grating (FBG). The SPR sensors are able to detect the liquid sample salinities through the refractive index variation of the different samples. In contrast, the FBG sensors estimate the salinity through the thermal dynamics of the samples. Results show a sensitivity of 164.0 nm/% and 12.5 pm/°C for the SPR and FBG sensors, respectively. Thus, the combination between the SPR and FBG sensors result in an improvement of the salinity monitoring of different samples, where a root mean squared error of 0.001% is obtained.