Waveguide СO2 lasers with controlled frequency selective resonator properties

The spectral properties of waveguide resonators having a configuration known as "Case I" are analyzed and compared when the reflectors are mounted directly next to the waveguide and when one of them is moved to a considerable distance from the waveguide. The conditions are determined under which the frequency and mode selectivities are increased in waveguide lasers with a dispersive resonator. Experiments are reported on a waveguide СO₂ laser in which "hard" selection of the vibrational–rotational transitions of the 10P and 10R branches took place; the continuous tuning range of the radiation frequency for 18 transitions was then 750 MHz. A study was made of a change in the form of the transverse laser radiation intensity distribution when the plane mirror was removed to a considerable distance from the waveguide.