Z-scan theoretical model for simultaneous n- and (n+1)-photon absorption

Abstract

We present a theoretical analysis of multi-photon absorption processes. We find an approximate closed-form expression of the normalized transmittance for a thin sample with two successive nonlinear absorption processes at a time ([Formula: see text]- and [Formula: see text]-photon absorption) in the presence of residual linear absorption. Our approach allows for simultaneous identification and evaluation of the nonlinear absorption coefficients and Rayleigh lengths of the incident elliptic Gaussian beam by fitting the open [Formula: see text]-scan traces.