用扫描近场光学显微镜技术研究金膜表面等离体子共振

表面等离体子波(SPW)可与入射光横磁波极化能量耦合并被共振激发,这种现象被称为表面等离体子共振现象(SPR)。主要利用扫描近场光学显微镜(SNOM)技术和表面等离体子共振现象技术相结合,来研究金膜表面等离体子共振。设计并建立了结构独特的新型Kretschmann型表面等离体子共振现象耦合装置,同时又设计了具有厚度梯度的表面等离体子的制备方法。在此基础上,测量了改变入射角条件下的表面等离体子共振曲线,测得该装置的等离体子共振角灵敏度为1°。并且对金膜表面进行表面等离体子共振条件下的扫描近场光学显微成像。实验结果表明,在共振时金膜表面的扫描成像比不共振时清晰,而且增加了很多细节。应用表面等离体子共振现象技术将可以明显提高扫描近场光学显微镜的信噪比、分辨力等性能。

Research of Surface Plasmon Resonance on Gold Film Using Scanning Near-Field Optical Microscopy

Surface plasmon resonance (SPR) is a phenomenon induced by the polarizing energy coupling and resonant exciting of surface plasmon wave and incident TM light wave. The SPR on gold film is studied with combination of scanning near-field optical microscope (SNOM) and SPR technique. A novel Kretschmann type of SPR coupling device with special structure is designed and set up, and the fabrication method of surface plasmon with thickness gradient is presented. Based on the above preparation, the curve of SPR is measured with varied incident angle conditions, and the angle sensitivity for SPR is 1°. The image of gold film surface is obtained with SNOM under PSR conditions, and it is found that the image is clearer under SPR condition than that without SPR and more details are distinguished. The performances, such as signal-noise ratio and resolution, for SNOM are greatly improved with the SPR technique.