Long distance beam propagation in colloidal suspensions: Comparison between theory and experiment

Abstract

It has been conjectured for some time that colloidal suspensions can act as artificial self-guiding media and support solitary beam-like solutions. The optical forces, along a diverging Gaussian beam, act to pull and retain the diffusing nanoparticles into its beam path. Consequently, the nanoparticle suspension acts to guide the diverging Gaussian beam and maintain the beam waist over a distance longer than its Rayleigh range. In this paper, we present a detailed analysis of beam propagation within nanoparticle suspensions. Using a recently developed theory by El-Ganainy et. al. (1), we seek to understand the beam dynamics by monitoring the scattered light from the particles along the propagation of the beam. An initial comparison of the theoretical and the experimental results shows interesting deviations due to the exponential nature of the optical nonlinearity.