Limitation of laser radiation power by carbon materials with a nonlinear optical threshold effect at a flat-top pulse shape

Abstract

The possibilities of using multivariate determination of carbon nanotubes properties based on the dependence data of the normalized transmission logarithm on the sample displacement in the case of Z-scan with an open aperture as well as on the total pulse energy in the case of fixed sample position measurements are studied. The radiation transfer equation for the threshold dependence of the absorption coefficient on the intensity of a flat-top laser beam is used. The data of physical and computational experiments showed the sensitivity of the measured curves with respect to the values of the constants of the optical and threshold energy fluence, as well as the beam waist radius. The possibility of multivariate determination of the properties of liquid carbon nanotube-based dispersed media with a nonlinear optical threshold effect and beam waist radius inside such samples has been established. Keywords: optical limiting, multivariate analysis, carbon nanotubes, Z-scan

Size effects and improved optical limiting efficiency for carbon nanotube composites with a tetra(cyclotriphosphazene)-substituted phthalocyanine ligand

“…During measurements of optical limitation, the cuvette with the substance was fixed at the focus of the lens. A more detailed description is presented in works 6,7 . The measurements were performed using a Nd:YAG laser Lotis TII LS-2147N at the second radiation harmonic λ = 532 nm with a single pulse duration τ = 20 ns.…”

“…When constructing the theoretical curve, the approach described in paper 6 was used. To improve the accuracy of determining nonlinear optical characteristics, the value of the parameter is determined at which the maximum coincidence of the beam radius experimentally measured by the CCD camera and that theoretically calculated by the dependence of the normalized transmission on the sample displacement in the case of Z-scanning with an open aperture.…”

“…When carrying out measurements, it was found that the beam radius determined with the proposed model from the Zscan curve with an open aperture, more accurately matches the value of beam radius measured by the CCD camera, with the parameter value a=0.8. Expression ( 3) is used to determine the radius of the Gaussian beam in the approach that is presented in detail in the article 6 .…”