Self-focused light propagation in a fully saturable medium: Experiment

We report observations of self-focusing and filamentation, i.e., the formation of one or more self-trapped beams, of ∼3 ns laser pulses in strontium (Sr) vapor. The experimental arrangement consists of a Sr vapor cell and a pulsed neodymium-doped yttrium aluminum garnet pumped dye laser tuned to the blue of the 461 nm transition in Sr. The spatial intensity distribution of individual self-focused beams has been measured at the exit window of a vapor cell by using a magnifying lens and video camera. Measurements of power dependence, spatial distributions, and scaling behavior for filament formation are in good agreement with theory over a wide range of vapor densities, laser detunings, and laser powers. © 1996 The American Physical Society.