3. Extreme events in optics: examples of nonlinear systems and dynamics

3.1 Effects and phenomena related to the propagation of light

The propagation of a light pulse in a guided medium is influenced by two types of effects: linear and non-linear. Linear effects, always present, correspond to the phenomenon of chromatic dispersion, which modifies the temporal profile of the pulse, while non-linear effects, present only at high intensities and linked to the electronic structure of the medium's molecules, modify the spectrum of the pulse by generating new frequencies. In this paragraph, we recall the main concepts of these two families of effects, which govern the spectro-temporal evolution of a pulse. Readers wishing an exhaustive description of these effects can consult the many specialized works in the field.