100 W, tunable in-band thulium fiber amplifier pumped by incoherently combined 1.9 µm fiber lasers

We detail the design and performance of a high efficiency in-band pumped thulium fiber amplifier operating at the 100 W level. Using a novel pumping architecture based on three incoherently combined thulium fiber oscillators at 1904 nm and a seed laser tunable from 1970–1990 nm, efficient amplificat...

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Bibliographic Details
Published in:Optics express 2023-08, Vol.31 (18), p.29245
Main Authors: Cook, Justin, Sincore, Alex, Vail, Nicholas, Krämer, Ria G., Goebel, Thorsten A., Roumayah, Patrick, Bryan, Joshua, Bodnar, Nathan, Nolte, Stefan, Richardson, Martin
Format: Article
Language:English
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Summary:We detail the design and performance of a high efficiency in-band pumped thulium fiber amplifier operating at the 100 W level. Using a novel pumping architecture based on three incoherently combined thulium fiber oscillators at 1904 nm and a seed laser tunable from 1970–1990 nm, efficient amplification is demonstrated in a high dopant concentration 25/65/250 µm thulium fiber. Here we use the 65 µm pedestal surrounding the core as a pump cladding to increase the cladding to core overlap and improve the overall pump absorption. Up to 89% slope efficiency is obtained with ∼100 W output power at 1990 nm. These results indicate that in-band pumping is a viable route to circumvent the thermal limitations associated with 793 nm diode pumping and provide a pathway for development of multi-kW laser sources in the 2 µm spectral window.
ISSN:1094-4087
1094-4087
DOI:10.1364/OE.487601