Comparative studies of optical limiting in fullerene and shungite nanocarbon aqueous dispersions

Optical limiting properties of natural carbon nanoparticles (Shungite carbon) and fullerene aggregates in aqueous dispersions were for the first time studied and juxtaposed. For the picosecond laser pulses both dispersions exhibited comparable optical limiting property, apparently due to nonlinear absorption (mainly TPA). In the domain of the nanosecond laser pulses, nonlinear scattering NLS is thought to be main optical limiting mechanism in the dispersions under study. Shungite carbon dispersion showed stronger optical limiting (being similar to CBS) in visible and IR, which we ascribe to its structure more favorable to the thermal relaxation processes responsible for the NLS mechanism.