Comparison of different processes for separation of glass and crystals using ultrashort pulsed lasers

Abstract

We investigate cutting of transparent materials using ultra short laser pulses with pulse durations in the sub to a few ps regime. All compared methods base on nonlinear absorption including ablation cutting and cleaving or selective etching supported by laser induced modification inside the bulk material. For most of the experiments samples of hardened glass (Corning Gorilla®) with thickness up to 700 µm were used, ablation cutting of sapphire is presented additionally. Absorption and modification inside the volume is analyzed in detail, aiming for tailored modifications. Besides optical microscopy a pump probe setup was used. We show results of time resolved absorption measurements of 6 ps pulses focused into the volume. We observe shielding due to the interaction region and accumulation effects influencing the modifications. First results on inscribing and cutting by using beam shaping indicate the importance of tailoring the shape and arrangement of the pulses temporally and spatially. The results presented for the different cutting methods supports an assessment of the individual potential and a selection of the applicable method based on the requirements

Burst mode with ps- and fs-pulses: Influence on the removal rate, surface quality, and heat accumulation

“…In the case of glasses bursts are used e.g. for welding 13 , writing of gratings or waveguides 14,15 or cutting based on filamentation 16 . For steel C75 and 12 ps pulses the influence of t B was investigated for two pulse bursts 17 .…”

Improved laser glass cutting by spatio-temporal control of energy deposition using bursts of femtosecond pulses

“…Therefore, by producing subsequent laser modifications along a certain trajectory with lateral distance of the order of a few µms, material weakening can be produced along a desired line, and pieces can be separated by applying some further mechanical cleaving. This is the principle of cutting by internal volume scribing [6]. Using this method, we cut a 500 µm thick Eagle glass in a single pass.…”

“…Because laser energy absorption is highly nonlinear, the machining process can be controlled very precisely, and detrimental thermal effects are minimized [4]. Focused ultrashort laser pulses may induce highly localized structural modifications, and, if the deposited energy density is particularly high, laser-induced stresses and irreversible volume modifications allow non-ablative cutting [5][6][7][8][9][10][11].…”

Transverse pump-probe microscopy of moving breakdown, filamentation and self-organized absorption in alkali aluminosilicate glass using ultrashort pulse laser

“…The nonlinear absorption of ultra short pulsed laser radiation in a transparent material offers a variety of different applications. It is a challenging task to control the energy deposition appropriately for tailoring the material modification suited to a specific process [1,2]. With regard to involume machining, different modification mechanism are applied e.g.…”