High average power is not always the answer for laser material processing. Processing speeds can be increased with more average power however; there is no gain in efficiency meaning that costs and/ or distortion can be greatly increased. A better solution would be to get more from the laser output i.e. a more efficient beam-material interaction. In recent years, GSI Group, Laser Division has undertaken a number of research initiatives to optimize lamp pumped Nd: YAG laser power and utilize it to its fullest capacity.
Work has centred on high average power (400W-2000W) continuous wave (CW) laser systems, which operate in continuous wave mode but can also pulse or modulate the output power, raising peak powers over 2 times their conventional CW rating. GSI Group pioneered this technique in early 1990 and offers several benefits in welding and cutting.
Currently conventional SM CW Fibre lasers have no peak power over maximum average power capability. This is due to the peak power limitations of the diode pump sources used. Significant lifetime degradation occurs if the junction temperature of a laser diode is increased during operation for any significant length of time which would normally be useful for welding and cutting applications (i.e. milliseconds and above).
This work describes a SM fibre laser with a repetitive short pulse capability where the peak power is significantly higher than the average power and with cut and weld performance enhancement but where diode life is not affected. The focus of this work is therefore laser cutting and welding with a SM fiber laser up to 400W average power with peak power enhancement in a range of materials and thicknesses.