一2017年一第3期仪表技术与传感器Instrument一Technique一and一Sensor 2017一No．3一
基金项目:国家自然科学基金项目(61302181);上海市自然科
学基金项目(14ZR1418400,14ZR1418500);上海市教委创新基
金项目(13YZ111)收稿日期:2016-04-27基于修正的长程表面等离子体波的折射率检测研究
刘一瑾1,杨海马2,刘海珊1
(1.上海工程技术大学电子电气工程学院,上海一201620;2.上海理工大学光电信息与计算机工程学院,上海一200093)一一摘要:为发挥长程表面等离子体波共振峰宽度小,共振曲线斜率大,降低共振角位置不确定性的优点,解决其严格对称结构难于传感的问题,文中在理论分析介质-金属薄膜-介质结构模型的色散和反射特性的基础上,实验研究棱镜耦合激发该结构中的修正的长程表面等离子体波用于传感,改变实验中的结构参数,检测含水率10.8%~38.8%的蜂蜜三结果表明:其共振峰宽度变窄,介质膜厚二金属膜厚等参数对衰减峰及其宽度和衰减深度等参量都会产生影响,检测的入射角与折射率的线性相关系数为0．9932,可较好地实现传感三关键词:修正;长程等离子体表面波;共振峰;共振角;反射;介质膜
中图分类号:TH744一一一文献标识码:A一一一文章编号:1002-1841(2017)03-0090-04
Refractive Index Detection Study Based on Modified Long-range Surface Plasmon Wave
LIU Jin 1,YANG Hai-ma 2,LIU Hai-shan 1(1.School of Electronic and Electrical Engineering ,Shanghai University of Engineering Science ,Shanghai 201620,China ;
2.School of Optical-Electrical and Computer Engineering ,University of Shanghai for Science and Technology ,Shanghai 200093,China )Abstract :To play to the advantages of long-range surface plasmon wave has the advantages of narrow width of the resonance peak,the greater slope of resonance curve and the reducing of uncertainty of the resonance angular position,solving its problems of the strictly symmetrical structure and it is unsuitable for sensing applications,based on the theory analysis of dispersion and reflection characteristics of media-metal film-media structure,the modified long-range surface plasmon wave was excited by prism coupling method for sensing was studied in experiment.Structure parameters were changed in experiments and the detection of a-queous 10.8%~38.8%of the honey was realized.Results show that the resonance peak width of the long-range surface plasmon wave is much narrower than that of the traditional surface plasmon wave.The characteristics of modified long range surface plas-mon wave such as peak attenuation,attenuation peak width and depth attenuation are influenced by changing the thickness of the metal,the thickness of the medium.The detected incident angle is linear to the testing refractive index,and the linear correlation coefficient is 0.9932,thus it is a good linear correlation and it is suitable for refractive index detecting.Keywords :modified;long-range surface plasmon wave;resonance peak;resonance angle;refraction;media film
0一引言
长程表面等离子体波(long range surface plasmon
wave,LRSPW)传输于中间为金属膜两侧为相同介质的对称结构中,是由金属膜两侧的表面等离子体波
(surface plasmon wave,SPW)电磁场的重叠耦合而产生的,LRSPW 的能量密度主要集中于介质而不是有
吸收的金属中[1-5],传输损耗比非耦合的SPW 小得多,能够传输更长的距离[6-7]三由于LRSPW 的对称性,使其在传感应用中受限,当金属膜两端介质折射
率差别不大时,也可激发宽度较窄的共振峰用于传感,叫做修正的LRSPW三由于共振峰宽度减小,使曲线的斜率更大,可以降低确定共振角位置时的不确定性三本文通过对修正的LRSPW 结构的电磁场和波动方程进行理论分析,得出其色散方程及反射率公式,研究棱镜耦合激发修正的LRSPW 的结构,进行实验,从实验结果中可以看出,其衰减峰的宽度比传统的SPW 窄1~2个数量级,因此更容易确定共振峰的位置,通过改变介质以及金属膜厚度,分析衰减峰特性的变化三采用棱镜耦合的方法激发修正的LRSPW,用于检测含水率10.8%~38.8%的蜂蜜,检测的入射角与折射率的线性相关系数为0.9932,具有较好的线性相万方数据