Externally Wavelength-Stabilized Single Mode Lasers with 65% Conversion Efficiency and 50 pm Spectral Width at 1 W Output
M. Wilkens, G. Erbert, H. Wenzel, A. Maaßdorf, J. Fricke, A. Knigge and P. Crump
Conf. on Lasers and Electro-Optics/Europe and European Quantum Electronics Conf. (CLEO/Europe-EQEC 2021), Munich, Germany, Jun. 21-25, virtual event, ISBN: 978-1-6654-1876-8, cb-p-2 (2021).
Dense wavelength beam combining (DWBC) techniques can be used to image many diode lasers into a single beam with minimal degradation of beam quality M295% (at 95% power) and conversion efficiency ηE. Systems based on DWBC of broad area lasers can be scaled into the many-kW class for use in material processing applications  . Laterally single mode diode lasers with wavelength around λ = 970 nm that use advanced waveguide designs (with lateral mode filter and extremely asymmetric vertical design) offer a path to much higher brightness  . Such lasers achieve high power Popt and efficiency ηE in continuous wave CW (Popt = 1 W, ηE = 65%, M295% < 1.1)  and pulsed (Popt = 18W, 3.3 ns 10 kHz, M295% < 2.2)  operation, whilst remaining close to the diffraction limit. When external λ-stabilization is performed via a diffractive element (grating), the operating characteristics are strongly affected by the interaction between external optical configuration and internal diode laser design, seen in Popt , ηE, spectral width Δ λ95% (at 95% power), λ-tuning range and beam stability. The λ-tuning range and Δ λ95% for each diode laser are especially important as this limits the number of emitters that can be combined and thus the maximum achievable power via DWBC.
Ferdinand-Braun-Institut gGmbH, Leibniz Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany
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