If there is one obvious trend in laser technology, then it is the rise of fiber lasers. Fiber lasers took over market shares from high-power CO2 lasers, as well as from bulk solid-state lasers in high-power cutting and welding. Major fiber laser manufacturers are currently addressing a number of new applications to conquer even more markets.
Among those high-power lasers, the single-mode systems offer features that make them desirable: They possess the highest brightness, and they can be focused down to a few microns and to the highest intensities. They also exhibit the largest depth of focus, which makes them best suited for remote processing. Still, they are difficult to manufacture and only market leader IPG Photonics (Oxford, MA) offers a 10 kW system with single-mode power. Unfortunately, there are no details available on their beam characteristics, particularly any possible multimode components that may exist along with the single-mode beam.
After about a decade of stagnation in upscaling high-power single-mode fiber lasers, it now seems feasible to develop a new generation of kilowatt-class fiber lasers with excellent beam quality. Output powers of 4.3 kW have been shown, limited only by the pump power. Major limitations for further upscaling are identified and ways to overcome these limitations have been identified.
It should be noted that it was the careful investigation of all known effects and a subsequent parameter optimization that led to the advances in fiber design and, finally, to new records in output power. A further upscaling and adaption of the fiber for other applications seem feasible and will be targeted next.