Advanced components for multi-kW fiber lasers

Donald L. Sipes Jr.; Jason D. Tafoya; Daniel S. Schulz; Benjamin G. Ward; Chad G. Carlson

doi:10.1117/12.909337

22 February 2012 Advanced components for multi-kW fiber lasers

Donald L. Sipes Jr., Jason D. Tafoya, Daniel S. Schulz, Benjamin G. Ward, Chad G. Carlson

Proceedings Volume 8237, Fiber Lasers IX: Technology, Systems, and Applications; 82370P (2012) https://doi.org/10.1117/12.909337
Event: SPIE LASE, 2012, San Francisco, California, United States

Abstract

We report on the development and performance of a key components that enable the construction of multi-kW fiber amplifiers for government and industrial applications that are both reliable and highly affordable. The usefulness of these components span the range from single frequency near diffraction limited kW class fiber lasers to multimode wide linewidth fiber lasers for welding and cutting applications. The key components for these amplifiers are a novel multi fiber-coupled laser diode stack and a monolithic 6+1x1 large fiber pump/signal multiplexer. The precisely aligned 2-D laser diode emitter array found in laser diode stacks is utilized by way of a simple in-line imaging process with no mirror reflections to process a 2-D array of 380-450 elements into 3 400/440μm 0.22NA pump delivery fibers. The fiber combiner is an etched air taper design that transforms low numerical aperture (NA), large diameter pump radiation into a high NA, small diameter format for pump injection into an air-clad large mode area PCF, while maintaining a constant core size through the taper for efficient signal coupling and throughput. The fiber combiner has 6 400/440/0.22 core/clad/NA pump delivery fibers and a 20/440 PM step-index signal delivery fiber on the input side and a 40/525 PM undoped PCF on the output side. The etched air taper transforms the six 400/440 μm 0.22 NA pump fibers to the 500 μm 0.55 NA core of the PCF fiber with a measured pump combining efficiency of 92% with zero brightness drop. The combiner also operates as a stepwise mode converter via a 30 μm intermediate core region in the combiner between the 20 μm core of the input fiber and the 40 μm fiber core of the PCF with a measured signal efficiency of 90% while maintaining polarization with a measured PER of 20 dB. We report the signal coupling efficiency and power handling capability as well.

Citation Download Citation

Donald L. Sipes Jr., Jason D. Tafoya, Daniel S. Schulz, Benjamin G. Ward, and Chad G. Carlson "Advanced components for multi-kW fiber lasers", Proc. SPIE 8237, Fiber Lasers IX: Technology, Systems, and Applications, 82370P (22 February 2012); https://doi.org/10.1117/12.909337

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