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Proceedings Paper

Inner-cladding pump reflector based on chirped volume Bragg gratings
Author(s): Lauris Talbot; Louis-Charles Michaud; Vincent Boulanger; Pascal Paradis; Martin Bernier
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Paper Abstract

The cladding-pumping scheme has made the power scalability of rare-earth-doped fiber lasers up to record levels possible by distributing the pump absorption along much longer fiber lengths. However, in addition to increasing the fiber cost and the cavity losses, a longer cavity length leads to enhanced detrimental nonlinear effects such as stimulated Raman scattering. As a way to reduce the required length of such lasers, we propose here an all-fiber laser architecture that makes use of a femtosecond-written chirped inner-cladding Bragg grating (ICBG) as a residual pump reflector. We report a 73% reflectivity of the pump power propagating in the highly multimode 125 μm-diameter inner cladding of the fiber made out of pure silica. This component was inscribed by using 400 nm femtosecond pulses and the phase-mask technique. Such a reflectivity was reached by optimizing the chirp of the grating and by inserting the fiber inside a hollow capillary with an outside diameter of 1 mm during the inscription. The latter reduces greatly the impact of the fiber’s curvature on the refraction of the writing beam. A larger writing area and consequently a stronger reflectivity could therefore be reached. The presence of this component at the output of a 21 m long erbium-doped silica fiber laser operating at 1.6 μm increased its slope efficiency from 20.5 to 25.1 % with respect to the injected pump power and increased its output from 22.8 to 29 W at 115 W of pump power.

Paper Details

Date Published: 21 February 2020
PDF: 8 pages
Proc. SPIE 11261, Components and Packaging for Laser Systems VI, 112610R (21 February 2020); doi: 10.1117/12.2546707
Show Author Affiliations
Lauris Talbot, Univ. Laval (Canada)
Louis-Charles Michaud, Univ. Laval (Canada)
Vincent Boulanger, Univ. Laval (Canada)
Pascal Paradis, Univ. Laval (Canada)
Martin Bernier, Univ. Laval (Canada)

Published in SPIE Proceedings Vol. 11261:
Components and Packaging for Laser Systems VI
Alexei L. Glebov; Paul O. Leisher, Editor(s)

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