Résumé
Optical limiting properties of singlewall carbon nanotubes suspended in water have been evaluated with 7 ns pulses at 532 and 1064 nm and compared with those of other materials. In order to determine the origin of optical limiting, we carried out a Z-scan experiment at 532 nm and 1064 nm at different input energies. We evidenced strong nonlinear scattering and a refractive effect with a negative nonlinear index. The kinetics of nonlinear transmission, from the nanosecond to millisecond time scale, was studied using a pump-probe set-up at 1064 nm. We observed cavitation bubbles growth at low input energy. The different nonlinear effects evidenced are discussed in terms of physical origin and in terms of broadband optical limiting efficiency.