Investigation on optical limiting mechanism of solubilized multiwalled carbon nanotubes

Some experiments of input-output and Z-scan were carried out to investigate the optical-limiting mechanism of solubilized multi-walled carbon nanotubes (M-CNTs). The results of those experiments were analyzed in detail and compared with the others; the conclusions revealed that the optical-limiting of solubilized M-CNTs had similar characteristics to the nonlinear absorption effect. A particular phenomenon of thick samples in the input-output experiments was studied and the influence of other mechanisms was discussed as well. Based on Z-scan theory, the third-order nonlinear indexes of the experimental material were calculated. The analyses approved that the nonlinear absorption effect should play a primary role in the optical limiting of solubilized M-CNTs. But, the discussion about thick samples also implied that other mechanisms could not be neglected, notably in the situation of thick medium was heated continually; the particular phenomenon might be caused by the cavitation of micro bubbles.