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Proceedings Paper

Numerical studies on a modified negative-branch confocal unstable resonator (MNBUR)
Author(s): Thomas Hall; Karin M. Grünewald; Jürgen Handke
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Paper Abstract

A modified unstable resonator, suitable for a laser with large gain medium cross section and a small or median output coupling, is presented. The spherical mirrors of this resonator form an off-axis negative-branch confocal unstable resonator. The special shaping of the scraper together with the negative-branch confocal unstable resonator configuration yields a laser output beam in the shape of a half-ring. In contrast to the conventional resonator with a ring-shaped output beam, the cross section of the half-ring is more compact and generates a lower structured far-field distribution, but the rotational symmetry disappears. For a rectangular medium cross section, the modified resonator is applicable, too. Some properties of such a rectangular modified negative-branch confocal unstable resonator (MNBUR) are investigated numerically. The theory is based on the integral equation of the Fresnel-Kirchhoff formulation of Huygens' Principle. The theoretical study pays attention to inaccuracies that may occur in mirror manufacturing. With respect to deviations from the specified mirror radius of curvature, the MNBUR does not show important differences to the performance of a conventional unstable resonator. The tilt of a resonator mirror affects the total coupling loss. The sensitivity of the MNBUR to output mirror misalignment is smaller than that of the common negativebranch confocal unstable resonator. A further important improvement achieved by resonator modification is an increased beam quality.

Paper Details

Date Published: 26 April 2007
PDF: 7 pages
Proc. SPIE 6346, XVI International Symposium on Gas Flow, Chemical Lasers, and High-Power Lasers, 634639 (26 April 2007); doi: 10.1117/12.739360
Show Author Affiliations
Thomas Hall, German Aerospace Ctr. (Germany)
Karin M. Grünewald, Langer Grund (Germany)
Jürgen Handke, Langer Grund (Germany)


Published in SPIE Proceedings Vol. 6346:
XVI International Symposium on Gas Flow, Chemical Lasers, and High-Power Lasers

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