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

Abstract

Abstract:We demonstrate the advantage of combining non-diffractive beam shapes and femtosecond bursts for volume laser processing of transparent materials. By re-distribution of the single laser pulse energy into several sub-pulses with 25 ns time delay, the energy deposition in the material can be enhanced significantly. Our combined experimental and theoretical analysis shows that in burst-mode detrimental defocusing by the laser generated plasma is reduced, and the non-diffractive beam shape prevails. At the same time, heat accumulation during the interaction with the burst leads to temperatures high enough to induce material melting and even in-volume cracks. In an exemplary case study, we demonstrate that the formation of these cracks can be controlled to allow high-speed and high-quality glass cutting.

Ultrafast Bessel beams: advanced tools for laser materials processing

“…This opens the route for high speed processing and separation of crystalline substrates. This method, applicable to brittle materials, can combine non-diffractive spatial techniques with temporally-controlled pulse sequences (bursts, tunable envelopes, tunable repetition rates) for a substantial process control [74,75]. This involves tuning the energy deposition for initiating the process while avoiding catastrophic uncontrollable damage or excess heat loading.…”

High-resolution material structuring using ultrafast laser non-diffractive beams

“…They can equally be used for direct write of ablative features in the bulk and on surfaces [54] or through drilling in transparent materials [55]. To grasp the essential features of non-diffractive beams in material processing, we will briefly point out several cases of using Bessel beams for high impact applications [40,[56][57][58][59][60][61][62], that are finding now their way into industrial-grade processes. These were recently reviewed in Ref [63].…”

“…Given the one-dimensional geometry of interaction, the relaxation of energy and the resulting material constraints occur radially, along the direction of the highest gradients, creating thus transverse forces of significant strengths. These features, and the resulting forces and stresses, are of interest when separation of matter is concerned and are thus becoming essential in large scale high-speed cutting and cleaving applications [57,58,64]. An example of glass cleaving operation [57] is given in Figure 2(a), emphasizing the scale and the quality of material separation.…”

Extremely high-aspect-ratio ultrafast Bessel beam generation and stealth dicing of multi-millimeter thick glass

“…High speed and high quality cutting of thin and thick glass is therefore an important technological problem. Interestingly, the recent development of stealth dicing of glass has enable to cleave glass at speeds in the range of 10 to 100 cm/s using lasers with a high repetition rate of several 100's kHz [1,2]. Stealth dicing is a two-step technique where the first step consists in generating with individual ultrafast laser pulses a series of high aspect ratio nanochannels which define a weakening plane, serving as a fracture initiator.…”

“…Now, we demonstrate a proof-of-principle application of the high energy Bessel beam shaper to stealth dicing of thick glass. For stealth dicing, high cone angles have been shown essential for high quality cleaving [1], but one of the key limitations for thick glass dicing is to generate material modification on a significant part of the thickness of the material. We demonstrate here that the multi-mm long Bessel beam allows for glass separation up to 10 mm soda-lime glass.…”