Stable self-trapping and ring formation in polydiacetylene para-toluene sulfonate

Abstract
Numerical simulations of two-dimensional beam propagation in polydiacetylene para-toluene sulfonate measured values for n2 > 0 and n3 < 0, where Δn = n2I + n3I2, predict stable self-trapping and a new phenomenon in which a spatial ring evolves from a Gaussian input beam. We interpret the numerical results theoretically, using the variational model of nonlinear Gaussian beam propagation.