Kerr media subject to counterpropagating optical beams in a plan-plan Pérot-Fabry cavity or optical feedback have been deeply studied for transverse pattern generation. Many theoretical developments in the cavity configuration predict the existence of localized structures (solitons). However, no experimental evidence of these structures has been given up to now. In the feedback configuration, the highly nonlinear regimes present rare and intense localized structures in space and in time. In this framework, we are interested in studying experimentally the localization of light in the both previous systems. The first part of this thesis is devoted to the experimental evidence of spatial solitons in a Pérot-Fabry Kerr plan-plan cavity with positive diffraction. Then we study this cavity submitted to negative diffraction. Propagative domain walls are observed. They are pinned by the spatial forcing coming from the inhomogeneous gaussian optical pumping profile that induces light localization. We study briefly the case of cavity without diffraction in which domain walls persist. We finally perform a study of highly nonlinear regimes in the optical feedback device using a statistical approach. We observe the emergence of rogue localized structures associated with the emission of a spatial spectral supercontinuum.
