Experimental Study on Near-Field Optical Microscopy Teaching with Metal-Coated Probes

Near-field signals, such as the localized field intensity generated by surface plasmon resonance (SPR), have important applications in optics, sensing, and nanotechnology. In the process of near-field imaging, high-quality probes can obtain more realistic sample topography and higher signal-to-noise ratios while suppressing irrelevant background optical information. Through the rational design and the application of metal coatings, near-filed optical signal acquisition can be significantly enhanced, and probe detection performance can be improved. Based on the effect of probe coatings, this paper designs a research-oriented experiment on “metal-coating-enhanced near-field signals.” Using pyramidal silicon probes with metal coatings evaporated onto their tips and a modified scattering-type near-field optical microscope (s-SNOM), this study performs near-field optical imaging on standard gratings to investigate the effect of metal coatings on scattering near-field optical signals. Experimental results show that metal coatings can significantly enhance the near-field optical signals. This study aims to reveal the enhancement mechanism of metal coatings on near-field signals and provide new perspectives and experimental foundations for research in the fields of optical sensing and nanophotonics.