Abstract
This paper details the use of novel beam shaping methods to improve the flexibility and speed of ultrafast laser micro-processes. The vector fields of a picosecond-pulse laser beam are shaped using a Spatial Light Modulator (SLM) and polarization optics, so that both the amplitude and direction of the electric field vectors are controlled with a high spatial resolution. This allows to shape the focal field landscapes obtained by focusing the beam with a low Numerical Aperture (NA) lens. A number of shaped vector beams are produced, including radially or azimuthally polarized vortex beams. All these beams are then used for surface ablation of titanium alloy substrates at low fluence to imprint Laser Induced Periodic Surface Structures (LIPSS). Thanks to their polarization dependent properties, LIPSS help to analyse the vector fields in the focal region. This analysis reveals for the first time how the orbital angular momentum associated with a vortex vector field induces complex focal field landscapes which fluctuate along the optical axis of the focusing lens. The produced shaped focal fields are also used for helical micro-drilling stainless steel and silicon substrates. The results are compared in terms of quality and efficiency, illustrating how the distinct machining properties associated with each beam make it best suited for specific processes or materials.
| Original language | English |
|---|---|
| Title of host publication | Proceedings of the 38th international MATADOR Conference |
| Publisher | Springer Nature |
| Chapter | Laser Processing |
| Pages | 105 |
| Number of pages | 10 |
| ISBN (Print) | 978-3-319-64942-9 |
| DOIs | |
| Publication status | Published - 27 Mar 2022 |