通过双探针近场光学扫描显微镜在银纳米线上实现近场激发和近场收集表面等离子体，用一个探针在银纳米线的一端近场激发表面等离子体，另一个探针近场探测银纳米线上的表面等离子体强度分布，得到强度分布图.强度分布图显示表面等离子体在银纳米线的一端被有效激发并且有一部分表面等离子体沿着银纳米线和基底的界面传播到了另一端.用有限元法对银纳米线内的传播模式进行数值模拟，结果显示银纳米线内存在两种表面等离子体传播模式，分别为基模和高阶模.沿着银纳米线和基底介质之间传输的基模表面等离子体由于传输环境稳定，散射损耗小，实际传输长度接近模式传输长度，达10 μm以上;而高阶模表面等离子体由于部分裸露在空气中受表面缺陷散射的影响，散射损耗大，实际传输长度远小于模式传输长度.研究表明: 以能量高度束缚的基模表面等离子体作为载体，不仅可以实现低损耗传输，还可以减小集成器件之间的信号串扰，有效提高信息传输的安全性，在集成光学中具有重要应用.

Surface plasmon polaritons propagting along the silver nanowire was studied by near field scanning optical microscopy with twoprobes. In the experiment, one of the probe connected tolaser is positioned on one end of the silver nanowire to exicte surface plasmon polariton in near field, and the other probe scans along the silver nanowire to collect surface plasmon polariton in near field. The experimental result shows that surface plasmon polaritons are excited by the probe efficiently, and someof them reach the distalend facet of silver nanowire by propagating along the gap of silver nanowire and silica substrate. Finite element method is used to calculate the field distribution of surface plasmon polaritons modes on silver nanowire, which shows there are two surface plasmon polaritons modes with one as fundamental mode and the one as high mode. The fundamental mode of surface plasmon polariton, with its energy bounded to the gap of silver nanowire and silica substrate, suffers less scattering loss and can reach the other end of the silver nanowire. And the high modeof surface plasmon polariton attenuates quickly due to the scattering on the surface deffects. With the fundamental mode of surface plasmon polariton as information carrier, the efficiency of integrated optical device can be increased for its low propagation loss. What is more, the security of information transmission is improved since theenergy of the fundamental mode is bounded to the gap without scattering during propagtion, which is important in optical conmunication.