Nano Letters 23, 9900

Scanning near-field optical microscope (SNOM) with nanoscale spatial resolution has been a powerful tool in studying the plasmonic properties of nano materials/structures. However, the quantification of the SNOM measurement remains a major challenge in the field due to the lack of reliable methodologies. We employed the point-dipole model to describe the tip–surface interaction upon laser illumination and theoretically derived the quantitative relationship between the measured results and the actual near-field electric field strength. Thus, we can experimentally reconstruct the near-field electric field through this theoretically calculated relationship. We also developed an experimental technique together with FEM simulation to get the above relationship experimentally and reconstruct the near-field electric field from the measurement by SNOM.