High peak power, high rep-rate pulsed fibre laser for marking applications

摘要

In this paper, we have studied in detail the effects of pulse reshaping and the impact on the performance of pulsed fibre MOPAs. It is shown that properly designing the active fibre and appropriately defining its saturation energy can control the pulse reshaping. As a result, high peak powers and maximum possible energy can be achieved without the onset of SRS. We have also reported, we believe for the first time, a pulsed fibre MOPA configuration, which maintains the peak power over a 5kW level for rep rates in excess of 200kHz. The MOPA configuration comprises a directly modulated 1080nm laser diode seed, followed by a two-stage all-fibre amplification unit and an additional delivery fibre. The average power is in excess of 12W, the pulse energy lies in the 0.1-0.5mJ range, the pulse duration varies between 10ns and 200ns, while the peak power remains constant at about the 5kW or 10kW level for rep rates in the range 10kHz to > 200kHz. To the best of our knowledge, this is the first time that such a pulsed laser performance is reported and it is expected to have a big impact in the industrial applications arena, such as the development of efficient and very fast marking machines. Finally, we have demonstrated, using accelerated aging tests, that it is possible to develop Yb~(3+) doped optical fibres that do not photodarken under maximum inversion conditions.