Z-SCAN WITH ARBITRARY APERTURE TRANSMITTANCE - THE STRONGLY NONLINEARREGIME

We consider theoretical models of nonlinear optical propagation suitab le for describing optical Z-scan measurements within the strongly nonl inear regime. In particular, we demonstrate the equivalence of two alt ernative descriptions of beam propagation from a thin nonlinear refrac tor, in which the transmission measurements are modelled using a recei ving aperture of arbitrary size. If nonlinear absorption is the domina nt process, then we predict that a localized peak within the normalize d transmittance will appear at the waist position and should be observ able if the nonlinear interaction is sufficiently strong. (C) 1998 Els evier Science B.V. All rights reserved.