New developments in high power fiber lasers based on alternative materials

Andreas Langner; Mario Such; Gerhard Schötz; Stephan Grimm; Florian Just; Martin Leich; Christian Mühlig; Jens Kobelke; Anka Schwuchow; Oliver Mehl; Olaf Strauch; Roman Niedrig; Björn Wedel; Georg Rehmann; Volker Krause

doi:10.1117/12.876978

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10 February 2011 New developments in high power fiber lasers based on alternative materials

Andreas Langner, Mario Such, Gerhard Schötz, Stephan Grimm, Florian Just, Martin Leich, Christian Mühlig, Jens Kobelke, Anka Schwuchow, Oliver Mehl, Olaf Strauch, Roman Niedrig, Björn Wedel, Georg Rehmann, Volker Krause

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Proceedings Volume 7914, Fiber Lasers VIII: Technology, Systems, and Applications; 79141U (2011) https://doi.org/10.1117/12.876978
Event: SPIE LASE, 2011, San Francisco, California, United States

Abstract

Sintering of Yb-doped fused silica granulates is a well established technique developed by the IPHT and Heraeus Quarzglas and it produces very homogeneous rare earth doped bulk silica core rods for fiber laser applications. By using a newly developed laser induced deflection (LID) technique we are able to pre-characterize directly the material absorption properties of the bulk material prior to the laser fiber production. The bulk absorption results measured by LID are without scattering effects and they are typically in good agreement with the total attenuation measured in the fibers. We achieved a fiber background loss of 20 dB/km. Furthermore, we present detailed studies of the refractive index homogeneity of the Yb-doped bulk materials and laser fibers to show the unique features of the Yb-doped bulk silica. Multimode double cladding laser fibers with an extra large mode area XLMA fiber design (core diameter up to 100 μm) have been produced from the Yb-doped bulk silica rods by two different techniques. One is a classical jacketing method; the other employs the stacking of un-doped, Yb- and F-doped rods and F-doped tubes. Different fiber types have been tested in different fiber laser setups. The influence of the fiber end cap properties on the fiber laser focus shift is discussed in detail. We have achieved fiber laser output powers up to 1.925 kW, limited only by the pump power. We also investigated the long term laser stability at different power levels.

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Andreas Langner, Mario Such, Gerhard Schötz, Stephan Grimm, Florian Just, Martin Leich, Christian Mühlig, Jens Kobelke, Anka Schwuchow, Oliver Mehl, Olaf Strauch, Roman Niedrig, Björn Wedel, Georg Rehmann, and Volker Krause "New developments in high power fiber lasers based on alternative materials", Proc. SPIE 7914, Fiber Lasers VIII: Technology, Systems, and Applications, 79141U (10 February 2011); https://doi.org/10.1117/12.876978

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