Breakdown of the sequence of active transitions in a waveguide CO2 laser with a selective resonator

Breakdown of the sequence of active transitions in a waveguide CO₂ laser occurred as a result of a change in the angle of inclination of a diffraction grating. This was accompanied by a change in the transverse distribution of the laser radiation intensity and was manifested at low rotational quantum numbers J. The observed effect was due to the characteristics of the frequency-selective losses in the selective waveguide resonator.