Investigations have been performed to explore ultrashort laser irradiation effects on the surface... more Investigations have been performed to explore ultrashort laser irradiation effects on the surface topography as well as structural and nonlinear absorption properties of a polymer CR-39. For this purpose, a CR-39 target was exposed in air to 25 fs, 800 nm Ti:sapphire laser radiation at fluences ranging from 0.25 J cm −2 to 3.6 J cm −2. The surface features, structural changes and nonlinear absorption were explored by AFM, Raman Spectroscopy and a Z-scan technique, respectively. Several topographical structures like bumps, explosions and nano cavities have been observed on the irradiated surface. Raman spectroscopy reveals changes in the fundamental structure of the polymer after the irradiation. Nonlinear absorption data contained by the Z-scan technique predict the dominance of three-photon absorption in case of pristine CR-39. Furthermore, nonlinear absorption (three or two photon) increases with increasing laser fluences and is well correlated with surface and structural changes revealed by AFM and Raman spectroscopy.
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Papers by Ali Ajami