Dynamics of the operation of a fast-flow laser with inhomogeneous excitation of the active medium in an unstable cavity

Numerical simulation is used to investigate the influence of spatially inhomogeneous steady-state pumping on the dynamics of operation of a laser with fast crossflow of the active medium through an unstable cavity. It is shown that, depending on the distribution of the pumping rate inside the cavity, the pumping may stabilise cw lasing or may lead to its instability. The appearance of an instability is associated with the formation, under the action of inhomogeneous pumping, of considerable transverse gradients of the steady-state gain and field intensity distributions. If the spatial pumping profile is characterised by a steep fall of the excitation rate near the optic axis of the cavity, the calculations predict — depending on the system parameters — not only cw lasing, but also various self-pulsing regimes and chaotic lasing.