title: Spatial ringing and central dark zone formation in absorptive nonlinear beam propagation.
abstract: We have observed the theoretically predicted central dark zone formation in a continuous-wave propagation experiment that is not due to thermal changes in the index of refraction. The effect has been observed in a pink ruby rod with argon-ion and dye lasers. The results confirm the requirements of an optically thick and highly saturated medium for experimental observation of the effect.
authors.forename: R S
authors.initials: RS
authors.lastname: Afzal
authors.forename: N M
authors.initials: NM
authors.lastname: Lawandy