Excitation of relaxation oscillations due to a shift of the emission frequency of a CO2 laser

The Maxwell equations and a five-reservoir kinetic model are used in a numerical analysis of the transient processes that occur as a result of a shift of the emission frequency of a single-mode CO₂ laser. The mechanism of these processes is identified: it involves excitation of relaxation oscillations of the active medium associated with a change in the gain as a result of a shift of the emission frequency along the profile of the active transition. A discrepancy is found between the relaxation frequencies calculated for small perturbations of a two-level system and the frequencies calculated on the basis of the above model. This is most probably due to the influence of the nitrogen mode. Ways of counteracting the transient processes as well as possible practical applications of these processes are considered.