Pulse profile and transitions to chaos in a laser with a saturable absorber

The dynamics of a single-mode CO₂ laser with a saturable absorber is investigated numerically allowing for phase relationships and offsets between the lines. A detailed study is made of bifurcation of stationary (steady-state) and periodic solutions in the case of zero offset. It is shown that in the system under investigation there are two possible scenarios of transition to chaos for the selected parameters of a CO₂/CH₃I laser: period doubling and intermittency. An analysis is made of a change in the spectrum of the characteristic Lyapunov exponents in the chaotic lasing range. The predicted pulsed profiles are in good agreement with the experimental results. It is shown that in a certain range of parameters a laser with an absorber exhibits a generalized multistability.