21 November 2017 New 808 nm high power laser diode pump module for space applications
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Proceedings Volume 10567, International Conference on Space Optics — ICSO 2006; 105671C (2017) https://doi.org/10.1117/12.2308064
Event: International Conference on Space Optics 2006, 2006, Noordwijk, Netherlands
Abstract
New pump module concepts had to be developed for space borne applications, because a simple transformation of terrestrial solutions to space requirements was often not useful. A planar approach has been chosen, which prevents inherent draw-backs of stacks.
Schwander, Heine, Lange, Smutny, Erbert, Pittroff, Tränkle, Hoffmann, Plum, and Traub: NEW 808 nm HIGH POWER LASER DIODE PUMP MODULE FOR SPACE APPLICATIONS

1.

LOW POWER PUMP UNITS

The proven modular concept of Tesat’s pump units builds on multiple “Laser Diode Benches”, which reduce the test effort and enable maximum flexibility wrt. electrical interfaces, optical output power, reliability requirements, and environmental boundary conditions. Tesat’s lower power Pump Modules typically come with two Laser Diode Benches in a 1- out-of-2 cold redundancy. They deliver up to 5W with a 0.9998 reliability over 5 years of continuous operation.

Fig. 1.

Laser Diode Bench as used for Tesat low power CW Pump Module Heads

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All modules are fiber-coupled and come with robust and really hermetically sealed housings (leak rates are below 5 x 10-9 mbar l/s leading to more than 72% of initial fill gas remaining after 10 years).

Fig. 2.

Tesat Pump Laser Head, 45*45*20 mm, 150 gr, truly hermetically sealed

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The emission spectrum of the standard low power modules is Bragg stabilized for low noise pump applications with low thermalization effort.

Fig. 3.

Bragg stabilized 5W emission spectra for 25°C, 30°C, 35°C,

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2.

HIGH POWER QCW PUMP CONCEPT

The high-power end of Tesat’s pump module product line is currently marked by a 1.5 kW QCW module, if equipped with 20 high power laser benches and a 800μm output fiber. It builds extremely compact with only 95x35x25mm3. It is based on Tesat’s experience of the space qualified low power pump modules, and shows the same key performances as power scalability and truly hermetically sealed housings. A redundant 1- out-of-2 configuration is also possible in the same housing at the expense of output power. Depending on the number of laser benches a big variety of output power and reliability requirements can be met.

Fig. 4.

QCW pump unit concept with 12 laser benches (for 700W peak power)

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The concept is based on the combination of individual Laser Diode Benches strictly avoiding the inherent drawbacks of vertical laser diode stacks. Each Laser bench has almost identical operation conditions leading to superior quality and reliability. No interactions are expected between the individual laser benches like catastrophic chain reactions as known from stacks.

High power laser diode benches, containing 35 emitters each on a 4.5mm mini-bar, have already been tested up to 250W QCW peak power without COD. Nominal peak output power is 70W – 100W per bench. Only reliable process technologies as AuSn hard-soldering are applied already known from low poer devices. Power derating has been selected for highest reliable use in space missions.

A demonstrator of the high power QCW module is currently under construction. It shall be used as a pump source in the BepiColombo laser test bed.

Fig. 5.

Preliminary design of QCW high power laser bench

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The work has been done in close cooperation of Tesat, FBH, and ILT. The funding support of the DLR (Deutsches Zentrum für Luft- und Raumfahrt) is gratefully acknowledged.

© (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Thomas Schwander, Thomas Schwander, Frank Heine, Frank Heine, Robert Lange, Robert Lange, Berry Smutny, Berry Smutny, Götz Erbert, Götz Erbert, Wolfgang Pittroff, Wolfgang Pittroff, Günther Tränkle, Günther Tränkle, Hans-Dieter Hoffmann, Hans-Dieter Hoffmann, Heinz-Dieter Plum, Heinz-Dieter Plum, Martin Traub, Martin Traub, } "New 808 nm high power laser diode pump module for space applications", Proc. SPIE 10567, International Conference on Space Optics — ICSO 2006, 105671C (21 November 2017); doi: 10.1117/12.2308064; https://doi.org/10.1117/12.2308064
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