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Proceedings Paper

High-beam-quality unstable-cavity infrared optical parametric oscillator
Author(s): T. Debuisschert; D. Mathieu; Jean Raffy; Loic Becouarn; Eric Lallier; Jean-Paul Pocholle
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Paper Abstract

We have implemented an Optical Parametric Oscillator (OPO) with an unstable cavity. The cavity is a telescope made of a concave mirror and a convex mirror. This latter is coated only in its center an is the pupil of the cavity. The nonlinear crystal is a 5 cm long LiNbO3. The OPO is pumped by a 20 ns Q-switch Nd:YAG laser and is operated at 1.9 micrometers for the signal and 2.4 micrometers for the idler. The OPO threshold is 7 mJ. For a pump energy of 30 mJ, the signal and idler energy produced is 9 mJ. Those results are comparable to those obtained with plane mirrors cavities. The near field of the output beam has an annular distribution imposed by the pupil. The distribution is not uniform but has 2 lobes located on opposite sides one from another. This uniformity can be improved increasing in the magnification factor from 1.2 to 1.33. The far field shows a central peak with side lobes in the vertical direction. This intensity distribution can be calculated from the diffraction of a plane wave by a uniform annular pupil similar to the near field intensity distribution. This indicates that the field is close to the diffraction limit in this direction. In the horizontal direction, there is peak which is twice as large as the previous one, and there is no side lobes. The field can be estimated to be 2 times the diffraction limit in this direction. This experiment shows that infrared OPO's with unstable cavities can produce beams close to the diffraction limit with a good energy conversion.

Paper Details

Date Published: 13 May 1998
PDF: 11 pages
Proc. SPIE 3267, Laser Resonators, (13 May 1998); doi: 10.1117/12.308105
Show Author Affiliations
T. Debuisschert, Thomson-CSF (France)
D. Mathieu, Thomson-CSF (France)
Jean Raffy, Thomson-CSF (France)
Loic Becouarn, Thomson-CSF (France)
Eric Lallier, Thomson-CSF (France)
Jean-Paul Pocholle, Thomson-CSF (France)

Published in SPIE Proceedings Vol. 3267:
Laser Resonators
Alexis V. Kudryashov; Pierre Galarneau, Editor(s)

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