Advanced Optical Fiber LSPR Sensor for High-Sensitivity Salinity Detection: Theoretical and Experimental Insights

A reflective salinity sensor based on the Localized Surface Plasmon Resonance (LSPR) effect with a no-core fiber (NCF) structure has been simulated and designed. First, the sensing mechanism of the optical fiber SPR sensor was analyzed. Next, the influence of the metal type, the thickness of the metal film, and the length of the sensing area on the SPR spectrum were simulated and compared. Based on the simulation results, the sensor was designed and experimentally implemented to achieve optimal performance. Experimental results demonstrate that the sensor achieves a sensitivity of 1.939 nm% within a concentration range of 0% to 25%. Additionally, it surpasses previous systems in terms of performance, mechanical durability, and repeatability. As a result, the reflective SPR fiber-based salinity sensor holds significant potential for future applications in environmental monitoring and ensuring the safety of drinking water.