Simulation study of near-field enhancement on a laser-irradiated AFM metal probe

A systematic study of near-field enhancement on a laser-irradiated atomic force microscope (AFM) metal probe is reported. The dependence of the electric field distribution on various parameters, like laser wavelength, tip curvature radius, half taper angle and tip-substrate distance, is numerically studied using the finite element method in this paper. The simulation results show that high field enhancement appears around the tip and is mainly concentrated under the apex of the tip when the incident laser interacts with the AFM metal tip. The results indicate that electric field enhancement easily appears when the AFM metal tip is irradiated by a higher frequency incident laser, with a similar phenomenon using a relatively sharp tip. In addition, as the tip-substrate distance increases, the peak electric field enhancement underneath the apex of the tip decreases. Based on the distribution of electric field enhancement, a new scheme combining an optical fiber probe and an AFM metal probe is proposed for nanolithography.