Simulations of the Near-Field Enhancement on AFM Tip Irradiated by Annular Laser Beam

The near-field enhancement underneath the AFM tip irradiated by a laser beam is widely utilized in various nanofabrication techniques, such as nano-welding, nano-manipulation, nano-etching and so on. In this paper, a numerical model of near-field enhancement on AFM tip irradiated by annular laser beam is established using COMSOL Multiphysics. The results show that when the AFM tip is irradiated by annular laser beam, strong near-field enhancement is induced at the apex of the tip. The field distribution curve with the substrate presents a saddle shape, which demonstrates that the annular beam irradiated the AFM tip produce an extremely high near-field enhancement between the particle and the tip. In addition, the results indicate that when the AFM tip is irradiated by the annular laser with higher frequency, the near-field enhancement underneath the apex of the tip increases correspondingly. Moreover, when the irradiation angle is 60 Deg and the irradiation distance is 65 nm, the near-field enhancement reaches the peak. Based on the numerical simulation of the near-field enhancement, the system of the AFM tip irradiated by annular laser beam can be anticipated for further application in the field of nanofabrication.