Dynamic Instabilities in Optically Pumped Lasers with Linearly Polarized Pump and Generated Laser Beams

We analyze the influence of light polari­zation on the dynamics of coherently pumped lasers using a single-mode ring laser model which considers a homogeneously broadened four-level medium. As typical in FIR laser experiments, we consider linearly polarized pump and generated laser beams. Phase diagrams as a function of cavity detuning and amplitude of the resonant pump field have been obtained, which show domains of stationary, oscillatory and chaotic output. We show that the laser is much more stable when the polarizations of the pump and generated laser beams are parallel than when they are orthogonal. In the later case the laser exhibits Lorenz-like dynamics at a reduced instability pump threshold.