SYNTHESIS AND OPTICAL PROPERTIES OF A NOVEL ORGANIC/INORGANIC HYBRID NONLINEAR OPTICAL POLYMER VIA SOL-GEL PROCESS*

 A new organic/inorganic hybrid nonlinear optical (NLO) material was developed by the sol-gel process of analkoxysilane dye with tetraethoxysilane. A NLO moiety based on 4-nitro-4'-hydroxy azobenzene was covalently bonded tothe triethoxysilane derivative, i.e. γ-isocyanatopropyl triethoxysilane. The preparation process and properties of the sol-gelderived NLO polymer were studied and characterized by SEM, FTIR, ¹H-NMR, UV-Vis, DSC and second harmonicgeneration (SHG) measurement. The results indicated that the chemical bonding of the chromophores to the inorganic SiO₂ networks induces low dipole alignment relaxation and preferable orientational stability.The SHG measurements also showed that the bonded polymer film containing 75 wt% of the akoxysilane dye has a high electro-optic coefficient(r₃₃) of 7.1 pm/V at 1.1 μm wavelength,and exhibit good SHG stability,the r₃₃ values can maintain about 92.7% of its initial value at room temperature for 90 days,and can maintain about 59.3% at 100℃ for 300 min.