Progress in high-energy-class diode laser pump sources
P. Crumpa, C. Freverta, F. Buggea, S. Kniggea, G. Erberta, G. Tränklea, A. Pietrzakb, R. Hülsewedeb, M. Zornb, J. Sebastianb, J. Lotzc, W. Fassbenderc, J. Neukumc, J. Körnerd, J. Heind and T. Töpferd
Published in:
Proc. SPIE 9348, Photonics West, San Francisco, USA, Feb. 07-12, 93480U (2015).
Abstract:
A new generation of diode-pumped high-energy-class solid-state laser facilities is in development that generate multijoule pulse energies at around 10 Hz. Currently deployed quasi-continuous-wave (QCW) diode lasers deliver average inpulse pump powers of around 300 W per bar. Increased power-per-bar helps to reduce the system size, complexity and cost per Joule and the increased pump brilliance also enables more efficient operation of the solid state laser itself. It has been shown in recent studies, that optimized QCW diode laser bars centered at 940...980 nm can operate with an average in-pulse power of > 1000 W per bar, triple that of commercial sources. When operated at pulsed condition of 1 ms, 10 Hz, this corresponds to > 1 J/bar. We review here the status of these high-energy-class pump sources, showing how the highest powers are enabled by using long resonators (4...6 mm) for improved cooling and robustly passivated output facets for high reliability. Results are presented for prototype passively-cooled single bar assemblies and monolithic stacked QCW arrays. We confirm that 1 J/bar is sustained for fast-axis collimated stacks with a bar pitch of 1.7 mm, with narrow lateral far field angle (< 12° with 95% power) and spectral width (< 12 nm with 95% power). Such stacks are anticipated to enable Joule/bar pump densities to be used near-term in commercial high power diode laser systems. Finally, we briefly summarize the latest status of research into bars with higher efficiencies, including studies into operation at sub-zero temperatures (-70°C), which also enables higher powers and narrower far field and spectra.
a Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Straße 4, 12489 Berlin, Germany
b JENOPTIK Diode Lab GmbH, Max-Planck-Str. 2, 12489 Berlin, Germany
c DILAS Diodenlaser GmbH, Galileo-Galilei-Str. 10, 55129 Mainz, Germany
d Lastronics GmbH, Winzerlaer-Str. 2, 07745 Jena, Germany
Keywords:
diode laser, pump sources, bars, joule-class, high efficiency, monolithic stacked arrays.
Copyright © 2015 COPYRIGHT SPIE--The International Society for Optical Engineering. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from SPIE.
Full version in pdf-format.