Homoclinic dynamics of the vibronic laser

Herewith we report on the nonlinear dynamics of the vibronic laser, it means the laser, in which the laser action is possible only due to phonons of the host crystal lattice. We have described such a system using five level model, in which the number of the coherently excited lattice phonons is included as one of the dynamical variables. We have shown that at certain values of control parameters, such as pump wavelengths and pump intensities, the system follows the homoclinic trajectory in the phase space and eventually passes to the chaotic state. It keeps traveling between two or more unstable fixed points. We have investigated the evolution of the homoclinic orbits with the change of the control parameters. The theoretical predictions have been proved by us experimentally in the short-cavity alexandrite laser. We demonstrate the homoclinic character of the laser output, occurring for different pump wavelengths and pump powers. Instead there are the regions of parameters for which we usually observe the stable CW action and pulsations can hardly be achieved.