Fig. 1. Schematic diagram of fiber optic SPR sensor

Fig. 2. D-shaped fiber simulation model

Fig. 3. Dispersion relationship of SPR

Fig. 4. Simulation results and performance comparison when the polishing thickness is 58.4 μm and the Ag film thickness is 30～50 nm

Fig. 5. Simulation results and performance comparison when Ag thickness is 50nm and polishing depth is 58.4～62.5 μm

Fig. 6. Experimental environment and sensor samples

Fig. 7. Experimental results

Fig. 8. D-shaped optical fiber humidity sensing results when the relative humidity changes from 30% to 90%