Laser-induced nanopatterning, ablation, and plasma spectroscopy in the near-field of an optical fiber tip

Abstract

We combine laser processing and the technique of a scanning near-field optical microscope (SNOM) for realization of laser-patterning on a nanoscale, laser ablation near the fiber tip, and micro-analysis of solid surface samples by laserinduced breakdown spectroscopy (LIBS). We describe an universal SNOM-like setup allowing to produce near-field laser patterns by laser heating and laser ablation, laser-induced breakdown spectroscopy, and atomic force microscope (AFM) topography investigation with the same optical fiber tip, which is used as near-field emitter or as probe. With solid Si and Al samples, three laser processing regimes were observed with increasing laser pulse energy: (1) cone formation (only for Si, smallest features with 500 nm width and 100 nm height), (2) formation of small craters (smallest features with 450 nm width and 250 nm depth), and (3) crater formation with a width of more than 2 μm with emission of evaluable plasma emission line spectra.