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Proceedings Paper • Open Access

Mixed garnet laser crystals for water vapour DIAL transmitter
Author(s): Rainer Treichel; Christoph Czeranowsky; Bilge Ileri; Klaus Petermann; Günter Huber

Paper Abstract

There are more or less well established technologies such as the optical-parametric-oscillator (OPO), the Raman-laser, and the Ti-Sapphire laser, which are able to emit laser light in the region of the water vapour absorption lines. For WALES the regions of about 935 nm, 942 nm, and 944 nm have been identified as the most suitable wavelength ranges. However, each of these laser designs is highly sophisticated. Current baseline for WALES is the Ti-Sapphire laser.

A fourth possibility to achieve these wavelength ranges is to shift the groundstate laser lines (938 nm and 946 nm) of the Nd:YAG laser by replacing Aluminium and Yttrium by other rare earth elements. Changes of the host lattice characteristics lead to a shift of the upper and lower laser levels. These modified crystals are summarized under the name of "Mixed Garnet" crystals. Only the Mixed Garnet lasers can be pumped directly with diode laser and use a direct approach to generate the required laser pulses without frequency conversion. Therefore no additional non-linear crystals are needed and a higher electric to optical efficiency is expected as well as single frequency operation using spectral tuning elements like etalons. Such lasers have the great potential to fulfil the requirements and to become the preferred transmitter concept for WALES as well as for follow up missions. Within a ESA study several crystal compositions have been grown, spectrally characterised and analysed.

Absorbed space radiation energy in the crystal lattice causes colour centres, which can reabsorb the pump and laser wavelength and consequently reduce the laser gain considerably. Co-dopants such as Chromium and Cerium are able to suppress the colour centres and are candidates for effective radiation hardening.

The results of the crystal tuning, the co-doping with different radiation hardeners and the radiation tests will be presented. There applicability for a space based water vapour DIAL transmitter will be discussed.

Paper Details

Date Published: 21 November 2017
PDF: 5 pages
Proc. SPIE 10568, International Conference on Space Optics — ICSO 2004, 105681B (21 November 2017); doi: 10.1117/12.2307963
Show Author Affiliations
Rainer Treichel, EADS ASTRIUM GmbH (Germany)
Christoph Czeranowsky, Univ. of Hamburg (Germany)
Bilge Ileri, Univ. of Hamburg (Germany)
Klaus Petermann, Univ. of Hamburg (Germany)
Günter Huber, Univ. of Hamburg (Germany)

Published in SPIE Proceedings Vol. 10568:
International Conference on Space Optics — ICSO 2004
Josiane Costeraste; Errico Armandillo, Editor(s)

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