Preliminary results on non-linear effects in Au-ion-doped glass materials irradiated by femtosecond laser pulses

Our research was motivated by the specific properties of noble-metal nanoparticles and their wide applications. The resonance frequency for noble-metal nanostructures is in the near-UV and visible spectral ranges, where most of the commercially-available lasers oscillate. This makes these materials attractive candidates for studying their properties in view of efficient applications. We investigated filaments formation in Au-ion-doped glass materials, transparent in the visible range, during irradiation by femtosecond laser pulses. Second harmonic generation in the media was observed as well. This proved the formation of polycrystalline structures inside the media after femtosecond laser radiation. Further, self-phase modulation and continuum were observed. Thus, the nonlinearity of the media is higher than that of glass not doped with noble-metal particles. The nonlinear effects in the samples were investigated in terms of the laser beam parameters. The laser energy applied was between 10 - 40 mu J. The wavelengths used were in the range 240 - 2600 nm, as generated by an optical parametric amplifier system (TOPAS). The regenerative Ti: Sapphire amplified laser system emits at a central wavelength of 800 nm with a pulse duration of 35 fs and 1-kHz repetition rate.