Highly efficient fiber coupling of laser diode bars with > 50% electro-optical efficiency out of the fiber core

Abstract

Fiber-coupled diode lasers have become an established source for many industrial applications due to their high wall-plug efficiency, minimal maintenance and cost per watt. To decrease system size and cost for cooler and driver, high coupling efficiencies have become more and more important. Recent developments in broad area laser diode bars (BALB) and beam shaping systems with micro-optical components are leading to new highly efficient fiber coupling. We present newly developed high power diode laser modules which are performing at outstanding efficiencies with smallest package design. The combination of recently designed laser diode bars on passive heat sinks and optimized micro-optics results in laser modules with up to 60W out of a 200μm fiber with a 0.22 NA and > 50% electro-optical efficiency out of the fiber core, based on only one laser diode bar. The applications for such laser diode modules range from pumping of fiber lasers and amplifiers, over materials processing to medical applications. The presentation of the technology will show a path to scale high-brightness laser systems to higher power levels and efficiencies. The combination of different coupling techniques will allow laser modules with 100W out of 100μm fiber core up to 1.6kW out of 400μm fiber core with electro-optical efficiencies of > 45%.