Abstract

There has been recent interest in the phenomenon of on-axis enhancement of an intense cw laser beam in a strongly absorbing, nonrefractive, nonlinear medium.^1,2 The purpose of this paper is to present experimental observations of this cw on-resonant enhancement (CORE) and the associated Fresnel fringe structure and narrowing (self-focusing) of the spatial profile. We use the collisionally broadened D₁ line of atomic sodium. We also illustrate the relatively close agreement of predictions¹ based on a simple model of homogeneously broadened two-state absorbers.

© 1984 Optical Society of America