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

TLDR

All compared methods rely on nonlinear absorption, such as ablation cutting, cleaving, or selective etching, supported by laser‑induced bulk modification. The study investigates cutting of transparent materials with sub‑ to few‑picosecond laser pulses, aiming to analyze and tailor volume absorption and modification. Experiments used hardened glass (Corning Gorilla®) up to 700 µm thick and sapphire, with ablation cutting, and employed optical microscopy and a pump‑probe setup to study laser‑induced modifications. Time‑resolved absorption of 6‑ps pulses showed shielding and accumulation effects, and beam‑shaping experiments highlighted the importance of tailoring pulse shape and arrangement, enabling assessment of each cutting method’s potential for selecting the appropriate technique.

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.