Abstract

The mode-medium interaction (MMI) in pulsed carbon-dioxide lasers results from the laser-induced medium perturbation (LIMP) effect. ¹ The LIMP effect is due to the faster vibration-translation (V-T) deactivation rate of the lower laser level compared to that of the upper laser level. Thus the rate of kinetic heating is affected by the presence of stimulated emission. Treating the lasing modecules as 3- level systems, and assuming that the lower level is deactivated essentially instantaneously, the volumetric heating rate Q is given by where v₂/v = 2.44 and v₁/ v=1.47 for lasing at 10.64 μm, g is the gain per unit length, I_S is the saturation intensity and I is the intensity. In Eq. (1) the first term results from collisions, and the second term, from stimulated emisssion.

© 1987 Optical Society of America