Ablation of thin metal films by short-pulsed lasers coupled through near-field scanning optical microscopy probes

Short-pulsed lasers have been proven to be useful tools for precise modification of electronic materials. In conventional lens focusing schemes, the minimum feature size is determined by the diffraction limit. Finer resolution is accomplished by combining pulsed laser radiation with near-field scanning optical microscopy (NSOM) probes. In this study, short laser pulses are coupled to a fiber-based NSOM in order to ablate thin metal films. A detailed parametric study on the effects of probe aperture size, laser pulse energy, temporal width, and environment gas is performed. The significance of lateral thermal diffusion is highlighted and the dependence of the ablation process on the imparted near-field distribution is revealed.