含有银纳米膜的棱镜中光束古斯-汉欣位移效应研究

The ■nchen shift from the prisms structure coated with silver nanofilm

古斯-汉欣位移是一种灵敏度极高的折射率测量办法,在温度、压力传感等方面有巨大的应用潜力,但测量精度要求较高。为解决测量的困难和提高古斯-汉兴测量精度,本文设计了一种棱镜-银纳米膜界面层,搭建了一套可测量多偏振态多角度古斯-汉兴位移的测量装置,以此测量了棱镜-空气和棱镜-银纳米膜不同界面的光束的古斯-汉欣位移,并对其物理机制进行了探讨。实验结果显示棱镜-空气界面的古斯-汉欣位移平均值是2.7 μm,棱镜-银纳米膜界面的古斯-汉欣位移平均值是 27.7 μm,比棱镜-空气界面的位移增大了约10倍。使用COMSOL multiphysics软件模拟了棱镜-银纳米膜以及棱镜-空气界面的电场分布,对比棱镜-空气的情况,表明在消逝场作用下,银纳米颗粒表面形成了较强光场分布,光场方向沿入射光电场振动方向;银颗粒表面光场和消逝场的叠加使得消逝场增强,从而导致棱镜-银纳米膜界面的古斯-汉欣位移增大。本工作为提高基于古斯-汉欣位移效应的生物传感器的灵敏度提供了一个可供选择的手段。

TheGoos-Hnchenshiftis a highly sensitive refractive indexmeasuremen t method,which has great application potential in temperature and pressure sensing,but has hig h requirements for measurement accuracy.In order to solve the measurement difficulties and improve the measurement accuracy of Goos-Hnchen,Inthis paper,wedesigna prism-silver nanof ilminterface layer and builda measuring device that can measure multi-polarization state and multi-angle Goo s-Hnchenshift.The Goos-Hnchenshift of the beam at different interfaces of prism-air and prism-silver nanofilm was measured and its physical mechanism was discussed.The experimental results show that the average Goos-Hnchen shift at the prism-air and the silver nanofilm interfa ces are 2.7μm and 27.7μm, respectively.The Goos-Hnchen shift at the silver nanofilm interface isenhancedmore than 10times compared with that atthe prism-air interface.The electric field distribution a t the prism-silver nanofilminterfaceandprism-airinterface was simulated using C OMSOL multiphysics software.Theoretical analysis demonstratesthat the strong local field generated by the silver nanopar ticles enhances the evanescent field,which contributes tothe improvementof the Goos-Hnc hen shift at the prism-silver nanofilm interface.The research work provides analternativestrategyfor improving the sensitivityof thosebiosensorsbased on the Goos-Hnchenshift eff ect.