Route to Chaos in a CO2 Laser with Injected Signal
It is well known that the equations for a single-mode laser can be reduced to the Lorenz equations and a chaotic behavior should be seen. However, this type of chaos has never been observed because of the actual values of the parameters in physical systems. Hence, it is necessary to introduce an external modulation or to have a multimode laser where the degrees of freedom are larger than three. In these systems, experimental results have been reported [3–4]. In this communication a transition to chaos by intermittency is numerically shown in a single-mode laser with an injected signal without any modulated parameter. We refer to a CO2 laser medium where the pressure broadening provides a homogeneous gain line. A CO2 laser system has a relaxation time (1/γ|| = 10−3s) much larger than the dipole decay time (l/γ┴ = 10−8s); hence, the single mode dynamics is described by the coupling between two degrees of freedom (rate equations). Introducing an external field whose frequency ωl is detuned with respect to the cavity resonance ω0 and the atomic transition frequency ωc, we have the three degrees of freedom necessary for the onset of chaos.
Unable to display preview. Download preview PDF.