  We investigate the use of ultrafast lasers exposure to induce localized
crystallization and elemental redistribution in amorphous dielectric
multi-layers, composed of alternating Si3N4and SiO2layers of sub-micron
thickness. Specifically,we report on the occurrence of a laser-induced
elemental intermixing process and on the presence of silicon nanocrystals
clusters localized within the multi-layers structure. The spatial distribution
of these clusters goes significantly beyond the zone under direct laser
exposure providing evidences of energy being channeled transversely to the
laser propagation axis at the interface of the nanoscale layers. Thanks to the
extreme conditions reigning during laser exposure, this process transposed to
various materials may offer a pathway for local and selective crystallization
of a variety of compounds and phases, difficult to obtain otherwise.
