双金属层表面等离子体共振传感器品质因子的研究

Optimization of the figure-of-merit of a bimetallic film surface plasmon resonance sensor

基于光学薄膜理论,研究了银-金双金属层表面等离子体共振(SPR)传感器品质因子的特征。首先,通过共振角处最低反射率的计算得到了双金属层的最佳厚度配比;其次,研究了最佳厚度配比下双金属层SPR传感器的线宽、灵敏度以及品质因子的特征。研究结果表明,随着双金属层中银膜厚度的增加(或金膜厚度的减小),传感器的灵敏度和线宽均减小,而传感器的品质因子增大。当双金属层SPR传感器中金膜厚度减小至0 nm时(单层银膜SPR传感器),传感器的品质因子达到最大值96.35 RIU-1。

Based on thin film optical theory, the figure of merit （FOM） of a silver-gold bimetallic film surface plas- mon resonance （SPR） sensor has been studied. First, the optimum thicknesses of a silver-gold bimetallic film which gave the minimum reflectance at the resonance angle were found. Then, the full-width-half-maximum （FWHM） , the sensitivity and the FOM of the bimetallic film SPR sensors with optimum thicknesses were investiga- ted. The results indicated that with increasing thickness of the silver film （or with decreasing thickness of the gold film） in the bimetallic film, the sensitivity and FHWM of the bimetallic film SPR ＇sensor with optimum thickness both decreased, but the FOM increased. When the thickness of the gold film in a bimetallic film was decreased to 0 nm, the SPR sensor afforded the highest FOM （96.35 RIU-1）.