Interaction of a soliton with a local defect in a fiber Bragg grating
  We study the interactions of a Bragg-grating soliton with a localized attractive defect which is a combined perturbation of the grating and refractive index. A family of exact analytical solutions for solitons trapped by the delta-like defect is found. Direct simulations demonstrate that, up to the numerical accuracy available, the trapped soliton is stable at a single value of its intrinsic parameter ("mass"). Trapped solitons with larger mass relax to the stable one through the emission of radiation, while the solitons with smaller mass decay. Depending on values of parameters, simulations of collisions between moving solitons and the defect show that the soliton can get captured, pass through, or even bounce from the defect. If the defect is strong and the soliton is heavy enough, it may split, as a result of the collision, into three fragments: trapped, transmitted, and reflected ones. 
William C. K. Mak and Pak L. Chu (Optoelectronic Research Centre,   Department of Electronic Engineering, City University of...