Formation of optical vortex lattices in solid-state microchip lasers: Spontaneous transverse mode locking - art. no. 063807

We experimentally investigate pattern formation in a solid-state microchip laser with a large Fresnel number. Controlling the reflectivity of the outp ut coupler can generate the stable square pattern of optical vortex lattice s. The formation of square vortex lattices is found to be a spontaneous pro cess of transverse mode locking within almost-degenerated mode families. Th e frequency of self-induced oscillation in square vortex lattices agrees we ll with the numerical calculation. The chaotic relaxation oscillation is fo und in square vortex lattices due to the multi-longitudinal-mode operation.