Improved optical limiting in dispersible carbon nanotubes and their metal oxide hybrids

The mechanism and performance of optical limiting in carbon nanotubes (CNTs) and their metal oxide hybrids are presented. The mechanism of nonlinear absorption (NLA) in dispersed CNTs was an effective three-photon absorption arising due to sequential transitions between the real excited states. The effect of nonlinear scattering was minimal, and it was found that the metal oxide immobilization on the CNT surface does not alter either the mechanism of NLA, or the optical limiting threshold. With limiting thresholds in the range of 0.37-0.46 J/cm(2), these highly dispersible MWCNTs and their hybrids are excellent optical liming nanocarbons. (C) 2011 Elsevier Ltd. All rights reserved.