Nonlinear scattering origin in carbon nanotube suspensions

In order to determine the origin of optical limiting in singlewall carbon n anotube (SWNT) suspensions, we carried out Z-scan and pump-probe experiment s at 532 nm and 1064 nm, for different input energies. We evidenced strong nonlinear scattering due to heat transfer from the carbon nanotubes to solv ent which induced solvent bubble growth and a nonlinear refractive effect. We noticed similar comportment at 1064 nm and at 532 nm, but with a lower b ubble growth threshold at 532 nm. At the microsecond timescale, we evidence d cavitation bubbles. We also evidenced, via emission studies, a phase chan ge corresponding to optical limiting threshold, which we associated to carb on nanotube sublimation. Optical limiting performances of water and chlorof orm suspensions were compared and solvent effects are discussed.