Regular and random output-power pulsations of a TEA CO2 laser with an intracavity nonlinear medium

The lasing dynamics of a pulsed atmospheric-pressure (TEA) CO2 laser with a nonlinear medium (semiconductor InAs or InSb) inside the cavity is experimentally investigated. It is observed that introduction into the CO2 cavity of nonlinear media having high nonlinear-absorption and a nonlinear refractive index leads, on the one hand, to a limitation of the emission intensity in the cavity and to an increase of the pulse duration (FWHM) from approximately 0.1 μsec to approximately 2 μsec, and on the other to appearance, on the output-power pulse envelope, of spikes having irregular amplitudes and durations, and separated by irregular intervals. It is established that the transition from the intermode-beat-induced regular pulsations to chaos has an emission-intensity threshold.