Sol-gel technology

because of the use of homogeneous liquid solutions and the ability to form gels at room temperature

provides an attractive route to the preparation of a three-dimensional inorganic network

especiallyfilms．Athree-dimensional network of organic／inorganic hybrid nonlinearoptical(NLO)materials can be prepared by doping optically active organics into sol-gel liquid solution or bonding organic chromophores with inorganics at the temperature below decomposition temperature(Td)of organic chromophores without risking the degradation of organic components．The properties of hybrid NLO materials Call be tailored by changing the starting chromophores The three-dimensional networks can restrict the dipole alignment relaxation of NLO chromphores

so the resulting NLO materials have high NLO susceptibility

low optical loss

high glass transition temperatures and good high-temperature stability．In this report

a new kind of bonded organic／inorganic hybrid NLO materials(DO3ASD)containing 4-Nitro-4’-amino azobenzene was synthesized through sol-gel process by using γ-glycidoxypropyl trimethoxysilane(KH560) as intermediates The preparation process and quality of DO3ASD were studied and characterized by FTIR

1H-NMR

UV-VIS

TGA

DSC

SEM and SHG measurements The results show that this bonded polymer film has a high NLO coefficient(d>33)of 5.79×10-7 esu

and exhibit good SHG stability

the d33 values cad maintain about 93.5％ of its initial value at room temperature for 90 days

and can maintain aboUt 60％ at 100℃ for 300min These facts demonstrated that the chemical bonding of the chromophores to the SiO2 networks can effectively reduce the dipole alignment relaxation of chromophores

thus lead to a better orientational stability．