NUMERICAL MODELING OF NONLINEAR OPTICAL LIMITING BY SUSPENSIONS OF CARBON NANOPARTICLES
The mechanisms of nonlinear optical limiting by aqueous suspensions of nanometric size carbon particles are theoretically investigated. We consider moderate input energy densities, which are not sufficient for heating of carbon particle up to the temperature of carbon sublimation (3770 K). Three tasks were self-consistently solved, gas-dynamics of formation and growth of vapor shell at the heated particle, light scattering by formed vapor bubble and radiation propagation through the perturbed medium and radiation optical limiting. Therefore, the system of self-consistent heat transfer equations for particle, water and vapor , gas-dynamics , radiative transfer and Me scaterring equations is solved Numerical modeling shows the predominant role of scattering compared to absorption and the sharp dependence of the cross section on the size of the vapour shell. Existence of nonlin-ear light scattering in aqueous suspensions of carbon particles in wide spectral range 400…1060 nm is demon-strated (for pulse durations of about 10 ns). Efficiency of nonlinear light scattering falling with pulse duration shortening is shown. The qualitative agreement of numerical modeling results with the experimental one is achieved.
Authors: N. G. Gogoleva
Direction: Physical Phenomena in a Solid Body, Liquids and Gases
Keywords: Carbon particles suspension, optical limiting, numerical modeling
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