Abstract

The obtaining of the steady-state regime of simultaneous oscillation on several given lines in CO₂ and CO lasers presents difficulties because of the competition between transitions. In Ref. ¹, it is shown theoretically and experimentally that the steady-state multiwave regime in a TEA CO₂ laser is possible at sufficiently high intensities of the light fields in the cavity. Due to the effect of “rotational or vibrational bottleneck" the competition between the transitions becomes considerably weaker. To weaken the competition, it is necessary to purposely create the conditions under which the field intensity in the cavity exceeds the saturation intensity of the CO₂ molecule operating transitions, which is determined from the expression: I_s = cπγ/τB, where c is light speed, γ is the collisional half width of the line, τ is the characteristic time of collisional relaxation, B is the integral Einstein coefficient for the centre of the vibrational-rotational transition. The field mechanism considered is applicable to multiwave oscillation at rotational transitions of both one band and various bands. In the last case, it is much easier to weaken the competition between the transitions. The effect of "vibrational bottleneck" comes into action at far lower saturation intensities, because it is determined by slower processes of vibrational exchange.

© 1994 IEEE