Z-scan analytical theories for characterizing multiphoton absorbers

Abstract

The open-aperture Gaussian-beam Z-scan measurements for characterizing an optically thin multiphoton-absorbing material were systematically investigated. Two widely used temporal profiles of the laser pulses on Z-scan traces were considered as well. The analytical polynomial expressions of Z-scan traces were presented for a thin sample with only one nonlinear process at a time [two-, three-, four-, or five-photon absorption (2PA, 3PA, 4PA, or 5PA)] and concurrence of two different processes (e.g., 2PA and 3PA, 3PA and 4PA, or 4PA and 5PA), respectively. A simple yet highly efficient approach was presented for identifying and evaluating the simultaneous n- and (n+1)-photon absorption coefficients. © 2009 Springer-Verlag.