Temperature effects in rf-excited CO 2 lasers with unstable resonators

Abstract

The qualitative and quantitative description of the laser tuning effect during a pulse forming has been described. The mechanism of the line hopping in the CO laser has been presented. A simple arrangement enabled observing the pulse evolution of all oscillating spectral transitions contributing in the total shape of the output pulse. As shown in the experiment, the jumps from line to line over the pulse duration give the sequence of lines, which is the subsequence of the static laser signature. Thus, the changes of the refractive index can be estimated by setting the static signature against the line hopping during the pulse operation of the laser. On the other hand, the changes of the refractive index during the pulse evolution have been measured directly with a Mach-Zehnder interferometer. The experiment has been performed on the slab-waveguide laser with an unstable positive branch optical resonator. The experiment allowed observing the dynamic evolution of the pulse in time and spectrum. The method of the investigations allows estimating the changes of a pressure and temperature during the pulse evolution, and can explain the effect of bulges observed at the output pulse shape.