Nonlinear enhancement of the efficiency of the second harmonic radiation produced by ultrashort laser pulses on a gold surfaceNonlinear enhancement of the efficiency of the second harmonic radiation produced by ultrashort laser pulses on a gold surface Peer-Reviewed Journal Publication Δημοσίευση σε Περιοδικό με Κριτές 2015-11-201997enAn unexpected nonlinear enhancement in the efficiency of the second harmonic generation as a function of the fundamental laser intensity is observed, when a gold surface is illuminated by few tens of GW/cm2 subpicosecond pulses of an excimer-pumped dye laser at grazing incidence. The evidence of this effect is tested by time resolved autocorrelation measurements. This enhancement is attributed to the thermal nonequilibrium, between the electron gas and lattice subsystems, produced by the subpicosecond laser pulses on the metallic surface.http://creativecommons.org/licenses/by/4.0/Optics Communications1-3137 174–180 Papadogiannis N.A Moustaizis Stavros Μουσταιζης Σταυρος Elsevier