Design and optimization of surface plasmon resonance sensor based on multimode fiber

We optimized the design of surface plasmon resonance sensor based on side polished multimode fiber using the method of finite element. The effects of the residual fiber thickness, gold layer thickness and the guiding modes on the depth, the full width at half maximum of the resonance dips were investigated numerically. The sensitivity to the variation in refractive index of analyte and the figure of merit are evaluated for design optimization. The results show that the fiber propagation modes have negligible influence on the resonant wavelength but have effect on the resonance strength. The optimal design was achieved at the residual fiber thickness of 75 mu m and the gold film thickness of 50 nm. The optimized sensor has an average sensitivity of 4989 nm/RIU in the refractive index range from 1.33 to 1.40.