Vol. 24, issue 03, article # 5

Geints Yu. E., Donchenko V. A., Zemlyanov Al. A., Panamarev N. S. Far-field temporal dynamics of laser beam passed through a thin nanocolloidal layer. // Optika Atmosfery i Okeana. 2011. V. 24. No. 03. P. 190-198 [in Russian].
Copy the reference to clipboard

Abstract:

We report on the experimental results of the temporal dynamics and formation of far-field diffraction patterns obtained when a low-intensity laser beam passes through a thin cell with metallic nanocolloids. The steady-state structure of the intensity distribution on a distant screen is shown to be formed in few seconds starting from the moment of laser beam incidence on the colloid and consists of several coaxial bright and dark rings. The ring's diameter and number vary depending on the solvent type and optical thickness of the colloid. The diffraction patterns depend also on the particle concentration and laser power. The theoretical interpretation of the observable peculiarities of diffraction patterns dynamics are carried out based on the free-space Kirchhoff diffraction integral and the analytical solution of heat transfer equation for a light absorbing medium.

Keywords:

nanocolloid, laser radiation, thermal self-defocusing, Fraunhofer diffraction