  Nonlinear optical property of transition metal dichalcogenide (TMDC)
nanosheet dispersions, including MoS2, MoSe2, WS2, and WSe2, was performed by
using Z-scan technique with ns pulsed laser at 1064 nm and 532 nm. The results
demonstrate that the TMDC dispersions exhibit significant optical limiting
response at 1064 nm due to nonlinear scattering, in contrast to the combined
effect of both saturable absorption and nonlinear scattering at 532 nm.
Selenium compounds show better optical limiting performance than that of the
sulfides in the near infrared. A liquid dispersion system based theoretical
modelling is proposed to estimate the number density of the nanosheet
dispersions, the relationship between incident laser fluence and the size of
the laser generated micro-bubbles, and hence the Mie scattering-induced
broadband optical limiting behavior in the TMDC dispersions.
