Highly nonlinear
optical properties of nanocarbon materials make
them perspective candidates for saturable absorption (SA) applications,
characterized by a short-term decrease in the optical medium absorption
at high incident light intensity. The nonlinear optical properties
and SA of aqueous suspensions of 5 nm detonation nanodiamonds (DNDs)
have been studied by the z-scan technique under irradiation
with nanosecond laser pulses at wavelengths of 532 and 1064 nm. The
saturation intensity and nonlinear absorption coefficient describing
the SA were obtained for concentrations of DND suspensions ranging
between 0.5 and 5 wt %. It was concluded that the single-digit DND
suspensions are suitable for optical limiting only at relatively high
intensities of incident radiation, with saturation intensities of
∼5.9 and 14.1 MW/cm2 for 532 and 1064 nm incident
excitation, respectively.