Coherent combining of high brightness tapered amplifiers for efficient non-linear conversion

P. Albrodt1, M.T. Jamal2, A.K. Hansen2, O.B. Jensen2, G. Blume3, K. Paschke3, P. Crump3, P. Georges1, and G. Lucas-Leclin1

Published in:

Opt. Express, vol. 27, no. 2, pp. 928-937 (2019).

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We report on a coherent beam combination of three high-brightness tapered amplifiers, which are seeded by a single-frequency laser at λ = 976 nm in a simple architecture with efficiently cooled emitters. The maximal combined power of 12.9 W is achieved at a combining efficiency of > 65%, which is limited by the amplifiers’ intrinsic beam quality. The coherent combination cleans up the spatial profile, as the central lobe’s power content increases by up to 86%. This high-brightness infrared beam is converted into the visible by second harmonic generation. This results in a high non-linear conversion efficiency of 4.5%/W and a maximum power over 2 W at 488 nm, which is limited by thermal effects in the periodically poled lithium niobate (PPLN).

1 Laboratoire Charles Fabry, Institut d’Optique Graduate School, CNRS, Université Paris Saclay, 91127 Palaiseau Cedex, France
2 DTU Fotonik, Department of Photonics Engineering, Technical University of Denmark, Frederiksborgvej 399, 4000 Roskilde, Denmark
3 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Straße 4, 12489 Berlin, Germany