Guided modes (electric field profiles, effective indeces) have been computed with the help of Comsol Multiphysics (http://www.comsol.com/) commercial Maxwell solver (version 5.1).

The pulse propagation equation was solved with the help of Matlab, by using the well established split-step algorithm, full details of the algorithm are available in G.P. Agrawal, "Nonlinear Fiber Optics," 5th ed. (Academic Press, 2013).