High-power, high-brightness, fiber-coupled pump modules enable high-performance industrial fiber lasers with simple system architectures, multi-kW output powers, excellent beam quality, unsurpassed reliability, and low initial and operating costs. We report commercially available (element™), single-emitter-based, 9xx nm pump sources with powers up to 130 W in a 105 μm fiber and 250 W in a 200 μm fiber. This combination of high power and high brightness translates into improved fiber laser performance, e.g., simultaneously achieving high nonlinear thresholds and excellent beam quality at kW power levels. Wavelength-stabilized, 976 nm versions of these pumps are available for applications requiring minimization of the gain-fiber length (e.g., generation of high-peak-power pulses). Recent prototypes have achieved output powers up to 300 W in a 200 μm fiber. Extensive environmental and life testing at both the chip and module level under accelerated and real-world operating conditions have demonstrated extremely high reliability, with innovative designs having eliminated package-induced-failure mechanisms. Finally, we report integrated Pump Modules that provide < 1.6 kW of fiber-coupled power conveniently formatted for fiber-laser pumping or direct-diode applications; these 19” rack-mountable, 2U units combine the outputs of up to 14 elements™ using fused-fiber combiners, and they include high-efficiency diode drivers and safety sensors.
Advances in high performance fiber coupled diode lasers continue to enable new applications as well as strengthen existing uses through progressive improvements in power and brightness [1]. These improvements are most notable in multi-kW direct diode systems and kW fiber laser platforms that effectively transform better beam quality into superior system performance and in DPSS (Diode pumped solid state) application striving to scale TEM00 (fundamental transverse mode) power. We report on our recent single-emitter based fiber-coupled product platform, the elementTM, that addressed these applications at 8xx/9xx nm with optical powers over 200W in a range of fiber core sizes down to 105um and 0.14NA (Numerical Aperture). The product is a culmination of numerous packaging improvements: improving wall plug efficiencies (~50% electrical-to-optical) while improving volume manufacturability, enabling lower costs, improving usable chip brightness by, < 20% over previous generation chips, and increasing the reliable output power to 15W per chip. We additionally report on current developments to extend the power of the product platform to as high as 300W. This will be realized primarily through new chip architectures projected to further increase the useable chip brightness by an additional 20 % and correspondingly scaling reliable output powers. Second order improvements are proposed in packaging enhancements that capitalize on the increased chip power and brightness as well as expand the package’s thermal capabilities. Finally, an extended performance roadmap will translate expected power advances and increasing volumes into a projection of relative $/W decreases over the next several years.
We report on the continued development of high performance fiber coupled laser diode modules at nLIGHT. We show that by optimizing the laser resonator design single emitter diode lasers can be tailored for high brightness or for reduced $/W applications. For instance, a fiber laser pump module based on 6 single emitter diode lasers couples efficiently into a 105 μm, 0.15 NA fiber with peak operating efficiency <59% and output power < 65W. These results are made possible by optimizing the diode laser slow axis brilliance and by increasing the optical to optical efficiency to 90%. We will also report on the development of tailored laser resonator that meets the power, brightness, and cost targets for industrial applications. For instance, a wider emitter has reliable performance of <18W of output power while maintaining the slow axis divergence required for coupling into a fiber with a 12 mm-mrad beam parameter product. The corresponding 50% increase in output power significantly improves the $/W performance. These results of high brightness and high efficiency demonstrate the pump technology required for next generation solid state, fiber lasers, and materials processing applications.
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