Experimental observation of a new type of intermittency in a CO/sub 2/ laser with modulated losses

Summary form only given. It is well known that near-resonant (i.e., close to subharmonic frequency) periodic perturbations depending on the type of bifurcation (supercritical or subcritical) can produce stabilizing or destabilizing shifts of the bifurcation points in dynamical systems, including CO/sub 2/ lasers. Recently it was shown theoretically that small deviations of the perturbation frequency from the subharmonic one in the nonfeedback control of chaos in CO/sub 2/ lasers results in a regular alternation between periodic and chaotic behaviors. Such type of temporal behavior has been identified as a new type of intermittency and called a breathing effect in dynamical systems. Here we report, to our knowledge, the first experimental observation of this type of intermittency resulting from near-resonant periodic perturbations. This effect is caused by the quasistatic periodic drift in the phase coming from the small detuning of the perturbation frequency with respect to parametric resonance in the system. Also, we show for different initial dynamical states that the phase of resonant perturbations of a given amplitude plays a key role in the stabilization or destabilization of the system. We found that depending on the initial state, the periodic perturbation can induce or suppress choatic behavior. We also demonstrate that a resonant perturbation can induce crisis of strange attractors in the bistability domain between chaos of the period-1 branch and chaos of the period-3 branch.