Abstract

We report the first observations of the cw self-bending effect¹ using an asymmetrical laser beam propagating in sodium vapor and discuss some concerns of practical and physical importance. The laser frequency was detuned below the D₂ resonance until the maximum self-bending angle was observed. At ~200°C the nonlinear refractive index was found to be predominantly Kerrlike (Δn ≃ n₂I) at experimental peak intensities up to ~220 W/cm². This result is inconsistent with our numerical calculations of the saturation of the anomalous dispersion that includes power-broadened hole-burning of an inhomogeneously broadened two-level system,² which predicts strong saturation of Δn. By analyzing either the self-deflection angle or the intensity at a single point in the far-field region as the input power was varied, we were able to determine that n₂ ≃ − 10⁻⁷ cm²/W. Self-deflection angles as large as 5.9 mrad or eight times the diffraction angle were observed, which is more than enough for some useful applications such as resonatorless optical bistability, optical switching, and interconnecting, nonlinear optical coupling, and radiation protection, the latter of which we have demonstrated.

© 1988 Optical Society of America