Pattern dynamics in an annular CO2 laser

Abstract. Competition among modes in an annular CO2 laser has been experimentally and numerically analyzed. During the coexistence of dierent patterns, each of them resulting from the interaction of two transverse modes with opposite angular momentum, chaos has been experimentally detected. A numerical model, derived from the Maxwell-Bloch equations and including symmetry breaking terms, enables the interpretation of the main experimental features. PACS. 42.55.-f Lasers { 42.65.Sf Dynamics of nonlinear optical systems; optical instabilities, optical chaos and complexity, and optical spatio-temporal dynamics { 42.65.-k Nonlinear optics