ASYMMETRY IN THE CHARACTERISTICS OF COLLIMATED AND UNCOLLIMATED OUTPUTS FROM A COPPER VAPOR LASER WITH A CONFOCAL POSITIVE BRANCH UNSTABLE RESONATOR

In a confocal positive branch unstable resonator, collimated output is extracted by placing a scraper mirror near the shorter focal length mirror. The output from the other end is generally not preferred because it has geometrical divergence in addition to the natural divergence. Recent experiments with noncavity lasers have indicated that asymmetry in the emission characteristics in the two counter directions could exist because of the fact that the radiation sees different radii of curvature mirrors during the first transit. Such behavior is particularly expected in high gain short inversion lifetime lasers like copper vapor lasers. In this paper. spatial and temporal characteristics of the output from the two ends of a PBUR CVL are studied. The results establish that significant asymmetry in the divergence of the two outputs exists. The temporal evolution of the divergence of the two outputs are different. The uncollimated output has better divergence compared to the collimated output.