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Proceedings Paper

High efficiency passively Q-switched Nd:YAG MOPA for spaceborne laser-altimetry
Author(s): Dietmar Kracht; Sven Hahn; Rafael Huß; Jörg Neumann; Ralf Wilhelm; Maik Frede; Peter Peuser
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Paper Abstract

For the spaceborne laser-altimeter (BELA) of ESA's BepiColombo mission a master-oscillator-power-amplifier system (MOPA) is presented. The specified system-requirement is a pulsed laser source with a nearly diffraction limited beam (M2 < 1.6) that combines high pulse energy of about 50 mJ at less than 10 ns pulsewidth and up to 20 Hz pulse repetition rate with the stringent environmental conditions at space missions. A low-mass (< 1.3 kg) and high optical-to-optical efficiency (> 15 %) laser setup is required. Stable operation at a temperature range of at least 25 K for the MOPA system and 15 K for the pump diodes has to be guaranteed. Both oscillator and amplifiers are longitudinally pumped by fiber coupled QCW laser diodes. The performance of a longitudinal pumped system is, because of the longer absorption path, less sensitive to pump wavelength variations due to temperature changes of the laser pump diodes. The pump-pulse duration of 200 μs represents as a trade-off between output energy and efficiency of the whole system. The Nd:YAG oscillator was passively Q-switched with Cr4+:YAG crystal as a saturable absorber. With 100 W of peak pump power a nearly diffraction limited (M2≈ 1.2) laser pulse with a duration of 2.8 ns and a pulse energy of 2.4 mJ was generated. The output beam of the oscillator was amplified in a two stage amplifier. A maximum of 62 mJ pulse energy was achieved by pumping each crystal with a peak pump power of 600 W.

Paper Details

Date Published: 28 February 2006
PDF: 8 pages
Proc. SPIE 6100, Solid State Lasers XV: Technology and Devices, 610021 (28 February 2006); doi: 10.1117/12.674044
Show Author Affiliations
Dietmar Kracht, Laser Zentrum Hannover e.V. (Germany)
Sven Hahn, Laser Zentrum Hannover e.V. (Germany)
Rafael Huß, Laser Zentrum Hannover e.V. (Germany)
Jörg Neumann, Laser Zentrum Hannover e.V. (Germany)
Ralf Wilhelm, Laser Zentrum Hannover e.V. (Germany)
Maik Frede, Laser Zentrum Hannover e.V. (Germany)
Peter Peuser, European Aeronautic Defence and Space Co. (Germany)


Published in SPIE Proceedings Vol. 6100:
Solid State Lasers XV: Technology and Devices
Hanna J. Hoffman; Ramesh K. Shori, Editor(s)

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