Pulsed laser operating on the first vibrational overtone of the CO molecule in the 2.5 — 4.2-μm range: 1. Multifrequency lasing

Characteristics of a pulsed, multifrequency electroionisation CO laser operating on the first vibrational overtone of the CO molecule are studied experimentally and theoretically. It is shown experimentally that a pulsed, multifrequency overtone CO laser is an efficient source of coherent radiation in the 2.5 — 4.1-μm region whose specific output reaches 50   J l^–1 amagat^–1 and the electro-optical efficiency amounts to 11%. A theoretical analysis based on experimental data shows the feasibility of obtaining overtone emission with efficiency as high as ~20%. The alternation of the intensity of vibrational bands in the overtone CO laser is discussed. This effect is caused by the cascade mechanism of formation of the emission spectrum. The comparison of experimental data with calculations showed that they agree well with respect to spectral and energy characteristics of the overtone CO laser. Moreover, it revealed the necessity of refinement of the kinetic model of the active medium of the CO laser for obtaining an adequate description of time parameters of a laser pulse.