title: Directionally selective optical limiting of femtosecond pulses in simple transparent two-layer systems.
abstract: Directionally selective nonlinear transmission behavior has been observed for simple glass-based two-layer systems in Z-scan experiments employing femtosecond pulses at a wavelength of λ=800 nm. Glass sheets of 1 mm thickness with a very thin surface layer (~2 μm) containing spherical Ag nanoparticles have been studied. In these samples, irradiating from the substrate side causes a strong transmission decrease via self-focusing of the beam and subsequent two-photon absorption in the thin layer, whereas the reverse direction may pass the sample without loss. This anisotropic optical limiting is discussed in terms of a numerical model in the limit of thin samples with respect to the Rayleigh range of the laser beam.
authors.affiliation: Physics Institute, Martin-Luther-University Halle-Wittenberg, Institut für Physik, Halle D-06099, Germany.
authors.forename: Sabitha
authors.initials: S
authors.lastname: Mohan
authors.forename: Heinrich
authors.initials: H
authors.lastname: Graener
authors.forename: Gerhard
authors.initials: G
authors.lastname: Seifert