Enhanced ablation using GHz-pulsed fs laser

Abstract

This paper presents a comparison between ablation results for various modes of laser operation: single pulsing, GHz bursting, and regular bursting. We start with the comparison of ablation thresholds of single ultrafast pulses with pulse widths ranging from 300 fsec to 3 psec. Those are contrasted with regular fsec pulse bursting at 20 ns pulse-to-pulse spacing, as well as GHz bursting with pulse spacing of 1.4 nsec. A variety of GHz milling results are presented and contrasted with single pulsing, as well as with 20nsec bursting, as the number of fsec pulses in a burst is adjusted from 3 pulse per burst, to 9, and 17, and for various scanning speeds. Material removal results are presented for milled transparent hard materials, specifically, fused silica, borosilicate glass, sapphire, and diamond. Aluminum and silicon are also included in this milling test for comparison. To maintain proper correlations, similar experimental conditions are used throughout, such as focused spot diameters, fluence, frequency of operation, and scan speed. The lasers used for this study are internally developed at IMRA for material processing. The data include results for 1045nm, 523nm, frequencies up to 1MHz, and power up to 5W.