SYMMETRY-BREAKING, DYNAMIC PULSATIONS, AND TURBULENCE IN THE TRANSVERSE INTENSITY PATTERNS OF A LASER - THE ROLE PLAYED BY DEFECTS

Pulsations which spontaneously break the cylindrical symmetry of a laser cavity geometry and the simultaneous appearance of topological defects in the transverse intensity patterns lead from periodic and quasiperiodic behavior to chaos and turbulence. We study these phenomena by numerical integration of the Maxwell-Bloch equations for the transverse pattern of a single-longitudinal mode laser with spherical mirrors and cylindrically symmetric boundary conditions. The motion of the defects appears in the form of travelling waves in the angular direction. This motion reduces the correlation of the intensity fluctuations at spatially separated points. One and two defect patterns are periodic or quasiperiodic, respectively. More complex patterns involving many moving defects display both the loss of temporal correlation (chaos) and the loss of spatial correlation (turbulence). A key to the independent motion of the defects is the excitation of a sufficient number of higher order radial and angular modes.