28 February 2006 High efficiency passively Q-switched Nd:YAG MOPA for spaceborne laser-altimetry
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Proceedings Volume 6100, Solid State Lasers XV: Technology and Devices; 610021 (2006); doi: 10.1117/12.674044
Event: Lasers and Applications in Science and Engineering, 2006, San Jose, California, United States
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.
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Dietmar Kracht, Sven Hahn, Rafael Huß, Jörg Neumann, Ralf Wilhelm, Maik Frede, Peter Peuser, "High efficiency passively Q-switched Nd:YAG MOPA for spaceborne laser-altimetry", Proc. SPIE 6100, Solid State Lasers XV: Technology and Devices, 610021 (28 February 2006); doi: 10.1117/12.674044; https://doi.org/10.1117/12.674044
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KEYWORDS
Optical amplifiers

Oscillators

Semiconductor lasers

Diodes

Nd:YAG lasers

Fiber amplifiers

Space operations

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