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Proceedings Paper

Mode-Medium Interactions
Author(s): D. Korff; S. Glickler; M. Tekula; A. Flusberg; A. Ballantyne; C. Duzy
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Paper Abstract

An instability in the output of a high-power unstable resonator cw CO2 thiser is analyzed in terms of a perturbative effect of an acoustic wave which is induced by laser heating. This may be either a three-wave process, in which the dominant mode of the laser couples to another laser mode separated from it by an acoustic frequency, or a two-wave process in which the acoustic wave modulates the cavity loss. Both processes depend on the refractive index perturbation by the acoustic wave. In the three-wave process, the two electromagnetic waves de-excite the lasing gas and the resultant heat deposition leads to the excitation of the acoustic wave. The phasing of the three waves is such that the interaction is unstable. It leads to an enhancement of the output coupling coefficient and in the nonlinear stage a complete shutdown of the laser. In the two-wave process, the acoustic wave is driven by nonuniform heating caused by nonuniformity of the optical eigenmode and changes of the cavity flux. Our analysis was extended to a simple one dimensional model of a supersonic laser, which was determined to be stable. A related problem of the alignment sensitivity of the cw CO2 laser was explained in terms of a temperature gradient along the gas-flow direction, which is transverse to the laser axis. The difference in path length, between the mirrors, through the density wedge can lead to unstable alignment.

Paper Details

Date Published: 30 December 1981
PDF: 20 pages
Proc. SPIE 0293, Wavefront Distortions in Power Optics, (30 December 1981); doi: 10.1117/12.932336
Show Author Affiliations
D. Korff, Avco Everett Research Laboratory, Inc. (United States)
S. Glickler, Avco Everett Research Laboratory, Inc. (United States)
M. Tekula, Avco Everett Research Laboratory, Inc. (United States)
A. Flusberg, Avco Everett Research Laboratory, Inc. (United States)
A. Ballantyne, Avco Everett Research Laboratory, Inc. (United States)
C. Duzy, Avco Everett Research Laboratory, Inc. (United States)

Published in SPIE Proceedings Vol. 0293:
Wavefront Distortions in Power Optics
Claude A. Klein, Editor(s)

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