Lin Kuan-Ting, Komiyama Susumu, Kajihara Yusuke
Opt Lett. 2016 Feb 1;41(3):484-7. doi: 10.1364/OL.41.000484.
We improve the spatial resolution and investigate the tip-sample coupling in a passive scattering-type scanning near-field optical microscope (s-SNOM), which probes thermally excited surface waves without any external light source. We study the spatial resolution, the intensity, and the decay behavior of the thermally excited near-field signals with different radii of curvatures of tungsten-tip apexes. We also study the tip size dependence of the interference pattern in the far-field region. The spatial resolution is closely related to the tip size, but the decay behavior of the near field is unrelated. These results suggest that the strength of the tip-sample coupling is unrelated to the tip size in the passive s-SNOM. We propose a theoretical model able to interpret the experimental data for the passive s-SNOM.
我们提高了空间分辨率，并研究了被动散射型扫描近场光学显微镜（s-SNOM）中的针尖-样品耦合，该显微镜在没有任何外部光源的情况下探测热激发表面波。我们研究了具有不同钨针尖顶点曲率半径的热激发近场信号的空间分辨率、强度和衰减行为。我们还研究了远场区域干涉图案的针尖尺寸依赖性。空间分辨率与针尖尺寸密切相关，但近场的衰减行为与之无关。这些结果表明，在被动s-SNOM中，针尖-样品耦合的强度与针尖尺寸无关。我们提出了一个理论模型，能够解释被动s-SNOM的实验数据。
