Multi-kilowatt peak power pulsed fiber laser with precise computer controlled pulse duration for materials processing

Abstract

We have developed pulsed fiber laser with computer controlled pulse duration and multi-kilowatt output peak power in a diffraction-limited beam. The diode laser as a master oscillator and Yb-based fiber amplifiers were used in a MOPFA configuration. The output pulse duration can be arbitrary selected in the range from 4ns to over 200ns with 1ns resolution. Pulse duration does not depend on the repetition rate and remains the same for all operational frequencies in the range from 10kHz to over 140kHz. The short length of the large mode area Yb-doped fiber was used to amplify the generated pulses to over 40kW peak power and several watt of the average power. The output pulse-to-pulse energy instability was less than 1% for all operational frequencies. Due to the single mode design of the delivery fiber, the measured output beam quality M 2 was found to be smaller than 1.05. The developed laser presents a solid-state design to be used in the industrial environment for applications where primary requirements are the beam quality, high repetition rate, small pulse-to-pulse energy instability and reliable laser operation on the real factory floor.

1 kW, 15 μJ linearly polarized fiber laser operating at 977 nm

“…Pulsed Yb 3+ doped fiber lasers emitting multiple-kW peak powers and mJ-range pulse energies are attempting to address many demanding applications [1][2][3] . Such fiber-based devices have numerous advantages over other types of lasers; compactness, maintenance-free operation, robustness (all fiber design) and high efficiency.…”