Tunable CO2 laser emitting sequential and hot transitions

The schematic model of a resonator with a reflection diffraction grating, providing a high frequency selectivivty, a wide spectral range, and a low loss level at a selected frequency, is studied theoretically and experimentally. The frequency-selective parameters of the resonator are calculated and analysed. It is shown that the dependence of the loss increment on the diaphragm diameter for a fixed frequency detuning Δν is nonmonotonic. Lasing at 100 lines of conventional bands and 36 lines of sequential and hot transitions is obtained. The minimum separation Δν_L between resolvable lines is found to be ~0.2 cm^-1.