Evolution of Cos-gaussian Beams in a Strongly Nonlocal Nonlinear Medium

The dynamical properties of cos-Gaussian beams in strongly nonlocal nonlinear (SNN) media are theoretically investigated. Based on the moments method, the analytical expression for the rootmean-square (RMS) of the cos-Gaussian beam propagating in a SNN medium is derived. The critical powers that keep the RMS beam widths invariant during propagation in a SNN medium are discussed. The RMS beam width tends to evolve periodically when the initial power does not equal to the critical power. The analytical solution of the cos-Gaussian beams in SNN media is obtained by the technique of variable transformation. Despite the difference in beam profile symmetries and initial powers, a cos-Gaussian beam always transforms periodically into a cosh-Gaussian beam during propagation and the transformation between the two beams revives after a propagation distance. Received 7 June 2013, Accepted 9 July 2013, Scheduled 26 July 2013 * Corresponding author: Rui-Pin Chen ([email protected]).