Two-dimensional optical lattices in a CO_{2} laser

D. Dangoisse, D. Hennequin, C. Lepers, E. Louvergneaux, P. Glorieux

Phys. Rev. A 46 5955 (1992)

Using a cavity with a large Fresnel number, a nontrivial large-scale order resulting from global multimode-interaction dynamics is found in the transverse structure of a CO2 laser beam. Two-dimensional optical lattices displaying several hundred phase singularities each have been observed. The symmetry properties of these far-field patterns and their associate temporal spectra are studied as a function of two control parameters: the Fresnel number and the transverse intermode spacing.