Photochromic sol-gel films containing dithienylethene and azobenzene derivatives: From the design of optical components to the optical data storage

This work is devoted to photoresponsive hybrid organic-inorganic materials prepared by the sol-gel method, using dithienylethene or azobenzene as phot osensitive chromophores. These photochromic units were covalently attached to the silica backbone as part of the main-chain and as a side group respec tively. The electrocyclization of dithienylethene or the isomerization of a zobenzene under irradiation cause local modifications of the optical proper ties of the host sol-gel polymers We took advantage of either high refracti ve index changes (>10(-2)) or material deformation of the sol-gel films to design optical components and to store information.