Self-focusing of CW laser beam with variable radius in rubidium atomic vapor

Self-focusing of cw laser beam in a rubidium atomic vapor was studied. The beam radius and power at the entrance of a rubidium vapor cell were variable parameters. A steep grow of the self-focusing threshold power for the small beam radius (≤30μm) was observed. Our experimental data are in a qualitative agreement with the recently published theoretical results obtained for a conventional non-resonant gas. Additional experiments in the resonance and transparent non-resonant media are suggested in order to check and extend our measurements.