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Proceedings Paper

Simple annular resonators with toric and helical mirrors
Author(s): Dietmar Ehrlichmann; Uwe Habich; Heinz-Dieter Plum
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Paper Abstract

Two simple annular resonators, each consisting of two total reflecting annular mirrors with radially concave curvatures, are described. The beam is guided to a coupling aperture in azimuthal direction by the azimuthal mirror shape. A resonator with tilted toric mirrors works like an azimuthal unstable resonator with two beams starting from a core oscillator of this resonator towards the coupling aperture. The function of this resonator is akin to conventional positive branch unstable strip resonators wrapped to an annular geometry. A resonator with helix-shaped mirrors emits one well defined beam. A numerical model of the resonators using a 3D-diffraction code and including effects of misalignment and saturable gain is presented. Numerical beam propagation techniques based on different approximations are compared. Due to the high azimuthal Fresnel number geometrical optics becomes applicable and turns out to be useful for a rough estimation of resonator design parameters. Experiments have been carried out using a diffusion cooled transverse RF-excited coaxial CO2-laser-gas discharge. Experimental data are compared with theoretical results concerning near-field and far-field patterns as well as misalignment sensitivity. Theoretical and experimental data correlate well. Both resonators yield more than 10 percent efficiency.

Paper Details

Date Published: 13 August 1993
PDF: 8 pages
Proc. SPIE 1868, Laser Resonators and Coherent Optics: Modeling, Technology, and Applications, (13 August 1993); doi: 10.1117/12.150638
Show Author Affiliations
Dietmar Ehrlichmann, Fraunhofer-Institut fuer Lasertechnik (Germany)
Uwe Habich, Fraunhofer-Institut fuer Lasertechnik (Germany)
Heinz-Dieter Plum, Fraunhofer-Institut fuer Lasertechnik (Germany)

Published in SPIE Proceedings Vol. 1868:
Laser Resonators and Coherent Optics: Modeling, Technology, and Applications
Anup Bhowmik, Editor(s)

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