Optical limiting effects in nanostructured silicon carbide thin films

We present the results of experiments on the interaction of nanosecond laser radiation at 532 and 1064 nm with nanostructured silicon carbide thin films of different polytypes. We have found the effect of optical intensity limiting at both wavelengths. The intensity of optical limiting at λ = 532 nm (I_cl ~10⁶ W cm^-2) is shown to be an order of magnitude less than that at λ = 1064 nm (I_cl ~ 10⁷ W cm^-2). We discuss the nature of the nonlinearity, leading to the optical limiting effect. We have proposed a method for determining the amount of linear and two-photon absorption in material media.