Ultrafast laser processing of transparent materials supported by in-situ diagnostics

Abstract

For the development of industrial NIR ultrafast laser processing of transparent materials, the absorption inside the bulk material has to be controlled. Applications we aim for are front and rear side ablation, drilling and inscription of modifications for cleaving and selective laser etching of glass and sapphire in sheet geometry. We applied pump probe technology and in situ stress birefringence microscopy for fundamental studies on the influence of energy and duration (100 fs – 20 ps), temporal and spatial spacing, focusing and beam shaping of the laser pulses. Applying pump probe technique we are able to visualize differences of spatio-temporal build up of absorption, self focusing, shock wave generation for standard, multispot and beam shaped focusing. Incubation effects and disturbance of beam propagation due to modifications or ablation can be observed. In-situ imaging of stress birefringence gained insight in transient build up of stress with and without translation. The results achieved so far, demonstrate that transient stress has to be taken into account in scaling the laser machining throughput of brittle materials. Furthermore it points out that transient stress birefringence is a good indicator for accumulation effects, supporting tailored processing strategies.Cutting results achieved for selective laser etching by single pass laser modification exemplifies the benefits of process development supported by in situ diagnostics.

Authors 5

1. Malte Kumkar corresponding

   TRUMPF (Germany)

   Affiliation as printed

   TRUMPF Laser-und Systemtechnik, Johann-Maus-Str. 2, 71254 Ditzingen, Germany;

2. Myriam Kaiser

   TRUMPF (Germany)

   Affiliation as printed

   TRUMPF Laser-und Systemtechnik , Johann-Maus-Str. 2 , 71254 Ditzingen , Germany;

   TRUMPF Laser-und Systemtechnik, Johann-Maus-Str. 2, 71254 Ditzingen, Germany;

3. Jonas Kleiner

   TRUMPF (Germany)

   Affiliation as printed

   TRUMPF Laser-und Systemtechnik , Johann-Maus-Str. 2 , 71254 Ditzingen , Germany;

   TRUMPF Laser-und Systemtechnik, Johann-Maus-Str. 2, 71254 Ditzingen, Germany;

4. Daniel L. Flamm

   TRUMPF (Germany)

   Affiliation as printed

   TRUMPF Laser-und Systemtechnik , Johann-Maus-Str. 2 , 71254 Ditzingen , Germany;

   TRUMPF Laser-und Systemtechnik, Johann-Maus-Str. 2, 71254 Ditzingen, Germany;

5. Stefan Nolte

   Friedrich Schiller University Jena

   Affiliation as printed

   Institute of Applied Physics , Friedrich-Schiller-University Jena , Albert-Einstein-Str. 15 , 07745 Jena , Germany;

   Institute of Applied Physics, Friedrich-Schiller-University Jena, Albert-Einstein-Str. 15, 07745 Jena, Germany;