Optical limiting performance of multi-walled carbon nanotubes

Abstract

The multiwalled carbon nanotubes (MWNTs) were synthesised by chemical vapor deposition and then dissolved in toluene solution. It is discovered experimentally that MWNTs have obvious optical amplitude limiting when the transmittance is measured by means of ps laser pulses with wavelength of 1064nm. In the case of low incident intensity, the transmittance varies linearly with incidenct intensity. However, the transmittance increases slowly under the condition of high incidenct light intensity and at last becomes saturated. Transmission is near 100% for weak incidenct light. But it is 30% when incidence intensity is 8GW/cm2. The calculated results based on three-photon-absorption theory agree well with the experimental results and it is inferred that the optical limiting of MWNTs results from its three-photon-absorption. The absorption coefficient γ is 1.36×10-20cm3/W2 and its corresponding absorption section σ′3 is 2.8×10-77cm6·s2.