Stabilization of transverse solitary waves by a nonlocal response of the nonlinear medium

TLDR

Optical pumping of atomic vapors can lead to self‑focusing of resonant laser beams. Saturation of optical pumping at low intensity permits transverse soliton formation with low‑power cw lasers, while the long lifetime of pumped atoms enables diffusion to carry excitation away from the interaction region. Numerical simulations and sodium‑vapor experiments demonstrate that the medium’s nonlocal response stabilizes the self‑trapped beam.

Abstract

Optical pumping of atomic vapors can lead to self-focusing of resonant laser beams. The saturation of the optical pumping process at low intensity allows the study of transverse solitons in the form of self-trapped laser beams, using low-power cw lasers. The long lifetime of the optically pumped atoms allows the atomic diffusion to transport the excitation away from the interaction region. Numerical simulations show that the resulting nonlocal response of the medium represents an important mechanism that stabilizes the self-trapped beam. The theoretical predictions are confirmed by experimental results from sodium vapor.