Ultrafast Fiber Laser Delivers High Power, Exceptional Beam Quality

A research group at Friedrich Schiller University of Jena in Germany developed an ultrafast fiber laser capable of delivering an average power that is more than 10× that of existing high-powered lasers. The technology aims to improve both speed and efficiency of industrial-scale materials processing.

Michael Muller, from Friedrich Schiller University’s Institute of Applied Optics and the Fraunhofer Institute for Applied Optics and Precision Engineering, introduced the laser at the OSA Laser Congress on Oct. 13.

The new laser externally combines the output of 12 laser amplifiers, rising above limitations caused by the fact that, in the process of light emission, lasers also generate waste heat. Fibers, which demonstrate a laser geometry with a high surface-to-volume ratio, effectively dissipate this heat — today’s high-powered lasers obtain an average power of 1 kW.

Beyond this power, though, the generated heat load degrades beam quality and establishes a limit.

The use of a dozen amplifiers allowed the research team, led by Muller and Jens Limpert, to show a laser able to produce 10.4 kW average power (at 80 MHz repetition) without any distortion or degradation of beam quality. Thermographic imaging of the final beam combiner revealed a marginal heating effect, meaning the addition of even more amplifier channels supported power scaling up to the 100-kW level.

Beyond applications in materials processing, the development will enable applications such as laser-driven particle acceleration and space debris removal — applications in extreme settings. Other uses identified by Muller include high-speed scanning and ablation cooling.

The work involving the investigation of novel applications at the high-power level and the transfer of the laser-based technology to commercial systems remains ongoing with the Fraunhofer Cluster of Excellence Advanced Photon Sources (CAPS). That collaboration involves the engineering of the laboratory setup into a more rugged design.

The Jena-based team, meanwhile, is focused on multicore fibers that offer the potential to deliver further superior performance in simpler and compacted system(s).