Effect of rotational level coupling on pulse sharpening in CO2amplifiers

The linear (small-signal) and nonlinear temporal response of CO
2
laser media was studied. Experimental results of the amplification of optical pulses whose duration is comparable to the inverse gain-bandwidth of the amplifying medium are described. Pulse narrowing, a consequence of nonlinear amplification, was observed. Computer calculations based upon a two-level model incorporating phenomenologically CO
2
rotational level coupling are compared with experimental observations.