| Summary: | An improved Drude-Lorentz model was proposed to describe the effect of annealing on the surface Plasmon resonance (SPR) sensor. In the new model, the grain structure is taken into account to describe theoretically the dispersion of gold films. Then the improved model is used to analyze the performance of SPR sensors before and after annealing. The results indicate that the grain structure of the gold film affect the resonance properties significantly. In our research, a considerable improvement in SPR fiber sensor performance is observed after annealing. The grain size of the gold film rises from 10.8 nm to 34.3 nm, and the absorption spectrum of the SPR fiber sensor becomes deeper and sharper, with the figure of merit increasing from 18.5 to 22.8 after annealing. Comparing with other sensor performance enhancement methods, the annealing progress does not change the sensor structure or add new modified layer. Therefore, most SPR sensors can be further annealed to improve the quality of the sensor after fabrication. This property makes the application of annealing very promising in optical sensing region.
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