Optimization and performance analysis of a D-shaped polymer optical fiber SPR sensor for selective detection of cadmium ions

This article explores the theoretical optimization and performance analysis of a surface plasmon resonance sensor utilizing a single-mode D-shaped polymer optical fiber for the detection of cadmium ions. In this structure, a sensing layer made of polyvinylpyrrolidone is employed over metal to protect it from environmental chemical reactions and selective sensing application of cadmium ions. Numerical investigations of the proposed structure have been carried out employing the finite element method. By optimizing the thickness of the metal, residual cladding, and sensing layer, the sensitivity and detection accuracy of the surface plasmon resonance sensor are estimated. The proposed sensor can detect the cadmium ions of concentration ranging from 0.5 ppm to 1000 ppm. The highest sensitivity (1500 nm/RIU), detection accuracy (29.6921), and figure of merit (64.4640 /RIU) of proposed sensors is observed at 1 ppm concentration of cadmium ions. Despite some variation, the detection accuracy and figure of merit remain high across all considered concentrations of cadmium ions, indicating the reliable performance of the sensor. Its optimal performance at lower concentrations is particularly beneficial for early detection and continuous monitoring of cadmium contamination.