Material micromachining using a pulsed fiber laser platform with fine temporal nanosecond pulse shaping capability

Abstract

We report on recent advances in laser material processing using a novel pulsed fiber laser platform providing pulse shape agility at the nanosecond time scale and at high repetition rates. The pulse shapes can be programmed with a time resolution of 2.5 ns and with an amplitude resolution of 10 bits. Depending on the desired laser performances, the pulses are generated either by directly modulating the drive current of a seed laser diode or by modulating the output of a seed laser diode operated in CW with electro-optic modulators. The pulses are amplified in an amplifier chain in a MOPA configuration. Advanced polarization maintaining LMA fiber designs enable output energy per pulse up to 60 μJ at 1064 nm at a repetition rate of 200 kHz with excellent beam quality (M 2 < 1.1) and narrow line widths suitable for efficient frequency conversion. Micro-milling experiments were carried out with stainless steel, in which processing microstructures of a few tens of microns in size usually represents a challenge, and aluminum, whose thermal conductivity is about 20 times higher than stainless steel. The results obtained with two metals having very different thermal properties using different pulse shapes with durations varying between 3 ns and 80 ns demonstrate the benefits of using lasers offering flexible pulse durations and controllable pulse intensity profiles for rapidly optimizing a process in different applications while using the same laser with respect to conventional methods based on pulsed laser with fixed pulse shapes. Numerous applications are envisioned in a near future, like the micromachining of multi-layered structures, in particular when working with the harmonics of the laser.

Dynamic Pulsing of a MOPA Pulsed Fiber Laser for Optimized Material Processing

“…In this regard, one finds that a variety of pulse widths and wavelengths are employed depending on the application requirements and desired experimental results [1,2]. Additionally, the temporal shape of the applied pulses has recently been shown to contribute significantly to the quality and to the material removal rates [3][4][5][6].…”

The Influence of the Processing Parameters on the Laser-Ablation of Stainless Steel and Brass during the Engraving by Nanosecond Fiber Laser

“…Laser ablation, a process in which material is removed layer by layer by systematic guidance of a laser beam over a sample, also known as laser engraving or laser milling, has been established in recent decades as an alternative to conventional methods of material removal in a wide range of industrial applications [1][2][3][4]. In addition to many outstanding properties of laser milling compared to conventional milling techniques, the recently increased interest of the industry [5][6][7][8][9] has been mainly influenced by the development of new laser sources which are more efficient and adaptable in terms of pulse energies and temporal shapes.…”

Process Optimization for 100 W Nanosecond Pulsed Fiber Laser Engraving of 316L Grade Stainless Steel

“…Over the years, much research effort has been expanded to remediate the effects of thermal build-up in the workpiece during high average power applications to make these lasers industrially acceptable. The research approach is generally to conduct a parametric survey to understand laser-material interactions and also investigate various laser processing strategies to mitigate the issues of thermal load [14][15][16][17].…”