Nonlinear photonic engineering: from NLO as a goal to NLO as a tool

Engineering of new nonlinear materials, structures and devices with enhance d figures of merit has acted over the last two decades as a major force to help drive nonlinear optics from the laboratory to real applications. In th is perspective, electrooptic polymers have triggered a currently maturing i ntegrated optics technology with a variety of industrial applications in vi ew We report here on a possibly major turning point in this field whereby n onlinear optical phenomena, while remaining a major functional end-goal per se, are being now implemented at the core of the elaboration process itsel f. Cycles of angularly selective optical pumping based on quantum interfere nces between multiphoton excitation pathways followed by relaxation via a r andomizing diffusion process are able to break the isotropy of adequate pho tosensitive media into a rich variety of controllable multipolar patterns. Their photoinduced symmetry reflects the multipolar symmetry of controllabl e polarization states of the coherent writing beams which can be permanentl y or dynamically imprinted on a variety of currently explored structures in cluding films, waveguides, gratings or microcavities. (C) 2000 Academic des sciences/Editions scientifiques et medicales Elsevier SAS.