LiNbO3棱镜耦合双金属薄膜表面等离子共振传感器

高折射率铌酸锂(LiNbO3)(2.202)为棱镜耦合激发的角度调制型表面等离子共振传感器,利用反射率公式优化单层银膜、金膜和双层银/金膜传感器薄膜的厚度,分别计算了优化厚度的传感器在检测样品折射率为1.330时的共振角、灵敏度、峰值半宽度(FWHM)和品质因数(FOM),理论计算表明:双层金属薄膜,随着金膜厚度的增加,传感器灵敏度增加,但峰值半宽度增加,品质因数下降.综合考虑,选择银/金(41/5)优化组合,传感器品质因数为优化的单层金膜(47 nm)传感器品质因数的2倍以上,另外,与常用的BK7玻璃棱镜耦合相比,LiNbO3棱镜耦合具有较大的样品动态检测范围.优化厚度的传感器实验检测糖水浓度表明:糖水浓度与共振角为线性比例关系.

Bimetallic thin-film surface plasmon resonance sensor based on LiNbO3prism coupling

A bimetallic layered surface plasmon resonance(SPR)based high refractive index LiNbO3prism coupling by angular interrogation is proposed.The thicknesses of single layer silver film,single layer gold film and bimetallic film sensor thin-film are optimized by reflectivity formula. The sensitivity,full-width-half-maximum (FWHM),resonance angle and figure of merit(FOM)of SPR sensor with optimum thickness while refractive index of tested sample is 1.330 are calculated.Theoretical calculation show that with the increasing of the thickness of gold layer in bimetallic film,both the sensitivity and FWHM of the SPR sensor increase,nevertheless FOM decrease.By comparison,the thicknesses of silver and gold in bimetallic film sensor are selected 41 nm and 5 nm, respectively.In addition,compared the commonly BK7 glass prism,the optimized SPR sensor has larger sample dynamic detection range. The experimental result shows that the concentration of sweet water is linearly relationship with resonance angle.