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At present, laser sources are widely used in many fields. Not only in laboratories, but also in sphere of medicine, manufacturing and military. Lasers are potentially dangerous to the eyes or sensitive optical devices, therefore it is necessary to develop optical limiters. One of the significant properties of carbon nanotubes is their optical limitation of laser radiation. Many works of scientific groups are devoted to materials for limiters, which include carbon nanotubes. However, they still have an increased interest. A particular role is given to such mechanism of nonlinear attenuation as scattering and absorption. Moreover, it is important not only their combined effect to increase the effectiveness of the limiters as a whole, but also the contribution of each of them with their combined effect. It is equally important to accurately determinate the concentration in which there is a strong attenuation of high-intensity laser radiation and minimal attenuation at low intensity. The nonlinear and linear optical properties of water-dispersed media with different concentrations of single-walled carbon nanotubes (SWCNTs) were obtained by optical density spectra, experimental Zscan data with an open aperture and a fixed location of the limiter. Radiation in single mode with duration of 16 ns at wavelength of 1064 nm from Nd:YAG laser was used. The linear transmittance of the prepared water dispersions of the SWCNTs ranged from 60% to 70%. Limiter with such working substances had attenuation coefficient 10 and 14 for the concentration of nanotubes 3.125 mg/l and 6.25 mg/l, respectively.
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