Instabilities and chaos in an infrared laser with saturable absorber: experiments and vibrorotational model

Ferdinando de Tomasi, Daniel Hennequin, Bruno Zambon, Ennio Arimondo

J. Opt. Soc. Am. B 6 45-57 (1989)

The instabilities and chaos in a CO2 laser containing SF6and 15NH3 absorbers have been studied as a function of the laser-control parameters. By making use of a phase-portrait analysis, the instabilities have been classified through their orbits in the phase space around the laser-with-saturable-absorber (LSA) fixed points. A chaotic regime, reached through a sequence of period-doubling bifurcations, has been observed for an instability of limit cycles around one fixed point. The transition between different instability operations presents an intermediate regime, which we have defined as the hesitation regime and have characterized through the fluctuations in the return times. The observed phenomena have been reproduced within a model, including the rotational—vibrational structure of the amplifier and absorber media. The numerical analysis has shown that the LSA time evolution, as described through homoclinic orbits in the LSA phase space, depends on the relative attractions of the saddle point and the saddle focus fixed points.