V. N. Chizhevsky

Experimental Switchings in Bistability Domains Induced by Resonant Perturbations

We show that a combination of a resonant perturbation which induces bistability in the system with the targeting technique based on the action of a short-lived pulse perturbation makes the nonfeedback control of nonlinear systems (not only in a chaotic state) more flexible and even competitive with OGYs method in the sense of fast switching between controlled orbits belonging to coexisting attractors. For different initial states we present several experimental and numerical examples of such a type of control, which does not require feedback system.

DYNAMIC STABILIZATION OF UNSTABLE PERIODIC ORBITS IN A CO2 LASER BY SLOW MODULATION OF CAVITY DETUNING

We demonstrate numerically and experimentally that a slow modulation of cavity detuning in a loss-modulated CO2 laser can stabilize unstable periodic orbits even when the system remains in a particular dynamical regime for adiabatic changes of the detuning. When the parameter changes faster than the transient response of deformation of the original periodic attractor, the system can evolve toward an unstable periodic orbit.

Experimental study of bi-directional pumping of a far-infrared laser

Abstract We show that bi-directional pumping can increase significantly the output power of optically pumped gas lasers. We demonstrate this effect in experiments with a methanol laser pumped by a CO 2 laser in a wide range of gas pressure for two different wavelengths, 119 μm and 170 μm. In our experimental conditions we obtain an enhancement of the maximal output power up to 70% as compared with uni-directional pumping of the same total intensity.

CO2 laser response to loss perturbation near period-doubling

Abstract The response of a CO 2 laser with losses modulated at frequency Ω to a loss perturbation of frequency Ω/2 as well as the response at the idler frequency is investigated experimentally and numerically near the onset of a period-doubling bifurcation under conditions in which the relaxation oscillation frequency of the CO 2 laser is larger than Ω. Strong amplification of the perturbation signal below the bifurcation point and deamplification above it have been observed. We have found that the laser response depends on the amplitude and phase of the perturbation signal and that the maximum amplification is proportional to a certain power of the perturbation amplitude which, for the parameters used, is −0.6. We show that the idler-to-signal ratio decreases with increasing perturbation amplitude. Reasonable agreement between numerical and experimental results has been obtained.

Phase-dependent scaling law for signal amplification and squeezing near period-doubling bifurcation in a CO2 laser

Abstract We study experimentally and numerically the effect of the phase of a periodic resonant perturbation-signal on a scaling law for signal amplification and classical squeezing in a CO2 laser with modulated losses in the vicinity of a period-doubling bifurcation. We obtain a π-periodical phase dependence in the scaling power which for maximal signal amplification has the value − 2 3 . Experimental results are in a good agreement with numerical calculations. The numerical simulations also show that in the phase range corresponding to classical squeezing the scaling power can take either negative or positive values, depending on the signal phase.

Nonlinear parametric effects near period doubling in a loss-modulated CO2 laser

Nonlinear parametric effects such as the suppression of period doubling, the shift of the bifurcation point, a scaling law relating the shift and the perturbation amplitude, an influence of the detuning on the suppression, reaching of the maximum gain between original and shifted bifurcation points, and a scaling law for idler power are experimentally observed near period doubling bifurcation in a loss-driven carbon dioxide laser which is subjected to periodic loss perturbations at a subharmonic frequency.