Scaling ultrashort laser pulse induced glass modifications for cleaving applications

Abstract

Ultrashort laser pulses allow for in-volume processing of glass through non-linear absorption. This results in permanent material changes, largely independent of the processed glass, and it is of particular relevance for cleaving applications. In this paper, a laser with a wavelength of 1030 nm, pulse duration of 19 ps, repetition rate of 10 kHz, and burst regime consisting of either four or eight pulses, with an intra-burst pulse separation of 12.5 ns, is used. Subsequently, a Gaussian-Bessel focal line is generated in a fused silica substrate with the aid of an axicon configuration. We show how the structure of the modifications, including the length of material disruptions and affected zones, can be directly influenced by a reasonable choice of focus geometry, pulse energy, and burst regime. We achieve single-shot modifications with 2 μm in diameter and 7.6 mm in length, exceeding an aspect ratio of 1:3800. Furthermore, a maximum length of 10.8 mm could be achieved with a single shot.

Ultrafast thin-disk multi-pass amplifier system providing 1.9 kW of average output power and pulse energies in the 10 mJ range at 1 ps of pulse duration for glass-cleaving applications

“…Comparison to published cleaving results shows a slightly increased surface roughness by a factor of 2. However, the feeding velocity accomplished in this work is increased by an order of magnitude [9,36,37]. Note that even higher speed would be allowed by the available parameters of the laser source.…”

“…However, several applications like e.g. suface structuring [6,7] or cleaving of glass [8][9][10][11] demand even higher average powers and pulse energies. To achieve this goal, several concepts were demonstrated during recent years.…”

A Strategy for Achieving Smooth Filamentation Cutting of Transparent Materials with Ultrafast Lasers

“…Other methods, such as diffraction optics, Bessel non-diffracting beams created with axicons, or intentionally astigmatic lenses (see, e.g., [11][12][13][14][15][16][17][18]), as well as the filament creation by a burst of pulses rather than by a single pulse [17,19], have also opened up a way where the total length of filaments, continuous or discontinuous, may be increased even by a single pass of the beam, thus allowing one to split materials of a greater thickness (up to few millimetres).…”

“…Despite the aforementioned advantages, a better and deeper level of understanding of the LFC process is still required to loosen constraints acting individually or in various combinations. These are: (i) a low separation rate of only a few mm/s or cm/s in some cases [4,13]; (ii) a lack of smoothness of resulting sidewalls of the cut [4,17,20]; and (iii) the need to use a high average power laser beam for separation-about a few hundreds of Wattsin particular for materials with thicknesses greater than several millimetres. The solution to avoid these shortcomings might be found based on an analytical model of the complex phenomenon of LFC with a pulse-periodic beam scanning over the sample with a high pulse repetition rate of up to several megahertz.…”

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

“…We note that a close concept has been developed by another group [32], used in Optical Coherence Tomography (OCT) imaging [33] and recently applied to induce up to 10 mm long modifications in glass [34]. However, the latter concept involves a first axicon in focusing geometry such that non-linearities, thermal lensing and optical damage, that we aim to avoid here, might happen for high average input power.…”