Chaos in aCO2laser with modulated parameters: Experiments and numerical simulations

A laser with parameters modulated at a frequency f may respond not only at that frequency and its harmonics nf, but also at that of its subharmonics f/n. When the order n of its subharmonics increases indefinitely, the response of the laser becomes irregular, though the system remains deterministic. Many approaches have been used to characterize these different behaviors and the associated attractors, in a ${\mathrm{CO}}_2$ laser containing an elasto-optic modulator. A quite important similitude has been remarked between the bifurcation diagram of the laser and that of the logistic map $x_{n+1\mathrm{}}$=1-μ$x_n^2$. More complex chaotic features have also been observed, e.g., generalized bistability between different attractors, and crisis when a chaotic attractor collides with an unstable periodic cycle. The influence of the rate of change of the driving parameters has also been studied. The experimental results show excellent agreement with those provided by the two-level model of the laser.