Nonlinear optical transmission in VOx nanotubes and VOx nanotube composites

Abstract

Optical-limiting behavior of vanadium oxide nanotubes is characterized for the visible and infrared spectral ranges using 8 ns pulses from a Nd:YAG laser with an $\text{f/40}$ optical system. Vanadium oxide nanotube dispersions were investigated in both water suspensions and embedded in solid polymethyl methacrylate films. In each case, these nanotubes exhibit strong optical-limiting at 532 nm (in comparison to carbon nanotubes); however, no nonlinear behavior is observed for 1064 nm. This suggests that a two photon or excited state absorption mechanism is responsible for the observed nonlinearity.