Near-field optical characteristics of Ag nanoparticle within the near-field scope of a metallic AFM tip irradiated by SNOM laser

Based on the near-field optical theory, the near-field characteristics of Ag nanoparticle within the near-field scope of a metallic AFM tip irradiated by optical fiber probe laser are carried out with finite element method. As the laser transmits in optical fiber probe, the light of the various modes is gradually turned off, remaining the HE₁₁ mode laser. Meanwhile, the evanescent field can be produced at the confined aperture, which will also stimulate the near-field enhancement phenomenon of metallic AFM tip and Ag nanoparticle with those extrema appearing in the apex of AFM tip, the upper and lower parts of Ag nanoparticle, and the upper and lower sharp boundary positions at the end of the tapered fiber probe. The related mechanism is revealed and near-field optical characteristics are also analyzed.