Process for realization of polymeric materials with second order nonlinear electro-optical properties and electro-optical devices made with said material

A process for the realization of polymeric materials with second order nonlinear electro-optical properties comprising the following steps:

• mixing a solution consisting of a chromophore with nonlinear optical properties and two or three hydroxy groups, a non-reactive solvent and an isocyanate compound with at least two isocyanate groups to form one or more bi- or tri-isocyanate NLO chromophores;
• isolation of said pure or bi- or tri-isocyanate NLO chromophores;
• dissolution of said bi- or tri-isocyanate NLO chromophores in a non-reactive solvent containing isocyanate reactive compounds consisting of acrylformamide, formamide and/or acylamides having as N substitutents, groups which are not reactive with isocyanate selected from hydrogen, alkyl, substituted alkyl, phenyl and substituted phenyl groups, in order to obtain a prepolymer mixture comprising said non-reactive solvents, said NLO bi- and tri-isocyanate chromophores, said isocyanate reactive compounds and reaction products of said NLO bi- and tri-isocyanate chromophores and said isocyanate reactive compounds;
• coating of a thin layer of said prepolymer mixture on a substrate and evaporation of said non-reactive solvents;
• cross-linking and poling of said thin layer on substrate, by means of heating and application of an electric field, in order a cross-linked and poled thin layer to be obtained;
• cooling of said thin cross-linked, and poled layer at ambient temperature maintaining the applied poling electric field;
• switching off the poling electric field.