The present project supports the creation, in 2010 at LabHC, of a team-project entitled « nanoparticles and sol-gel for photonics » that involves the participants in this “young researcher” project and that is led by the project carrier. The work we propose to achieve aims at developing: • a know-how for the fast inscription of permanent or updatable multicolour micro-patterns by an “all-optics” way and by an “electrical” way. The “all-optics” approach is based on the use of lasers emitting at different wavelengths (UV and visible) and enables the treatment of large surfaces with a resolution of the order of few micrometers. The electrical writing is based on the use of an Atomic Force Microscope (AFM) and allows the achievement of coloured patterns with a sub-micrometric resolution. This technique can be, eventually, coupled with the optical approach. This know-how is based on the use of titanium dioxide matrices, in which we will reduce and oxidize metallic nanoparticles, successively. • a knowledge, on the light-matter interactions that lead to the formation, deformation and destruction of the metallic nanoparticles, on the colour of sets of nanoparticles (heterogeneous and diluted NP; homogeneous NP with particular shapes; NP in strong interaction), and on the plasmonic coupling between close metallic nanoparticules. The developed know-how will provide a technique for direct inscription of updatable colour patterns requiring neither chemical nor thermal post-treatment. It is based on the control of the growth conditions of metal nanoparticles in solid matrices of porous titanium dioxide and benefits from the photochromic behaviour of these compounds. This know-how, based on the synthesis of sol-gel thin films, the control of the photo and electro-inscription processes and an appropriate modelling, presents the following innovative features: - inscription of multicolour patterns on the same sample - Sub-micrometer spatial resolution - reversible or permanent patterns (optional). - Fast inscription (of the order of few seconds). The writable or re-writable, high-resolution and coloured materials that will be developed, well complement the available solutions for photo-inscription. They should find applications in areas such as image reproduction, data storage or product-marking for anticounterfeiting and traceability. One strength of this project lies on the multidisciplinary approach. The project involves : -chemists for the sol-gel elaboration of mesoporous films and their structural charcaterization at atomic and nanometric scales; -physicists and opticists for the development of inscription processes and for the optical and structural characterization of nanoparticles grown in the matrices; -theoreticians in electromagnetic optics for the modelling of the optical properties of the nanomaterials.