This thesis examines the dynamical behaviour of solitons which are affected, when entering a fiber-optic waveguide, by a slight distortion of profile as compared to the stationary profile in the guide. Our theoretical model combines the propagation equation of the electric field (Non-Linear Schrödinger Equation) and the system of equations of evolution of the physical parameters of the pulse (derived from the collective coordinates theory). We establish a general mapping which reveals an unsuspected diversity of dynamic behaviour around the stationary state of the pulse, in relation with the initial perturbation of the pulse's profile. This mapping establishes a classification of solitons in two broad categories, which correspond to light pulses that generate radiation during their propagation and to non-radiating pulses, respectively. Within each of these two broad classes of pulses, we demonstrate the existence of different kinds of atypical behaviour, which we qualify as hyperthermic solitons (hot solitons), hypothermic solitons (cold solitons) and isothermic solitons, which correspond respectively to pulses that propagate in a highly stable manner with an energy level higher than, lower than, and equal to the energy of the stationary state. On the borders of the domains of existence of these various types of solitons, we find hybrid behaviours, corresponding to solitons that cool during propagation, due to a significant loss of energy caused by an intense radiation, and which change state (from hyperthermia to hypothermia, or from isothermal to hypothermia). Finally, the radiation emitted by a light pulse is not identified as being a continual process, but rather as a ball of energy emitted in the beginning of propagation, and its suppression in the waveguide is considered as practicable
