The Synthesis Of NLO Chromophore And Application Of NLO In Carbazole Polymer Photorefractive System

NLO is an important component of photorefractive systems. Photorefractive systems obtained better photorefractive properties when 1-n-butoxyl-2,5- dimethyl-4-(4′-nitrophenyl-azo)benzene (BDMNPAB) and 2,5-dimethyl-4 -(4′-nitrophenyl- azo) anisole (DMNPAA) were used in it. However, there were few reports about the research on the technology of these NLO. Two nonlinear chromophore containing azo group, BDMNPAB and DMNPAA, were synthesized in this paper. Reaction condition of products was discussed.Structures and properties were characterized. On this basis, photorefractive effect of carbazole doped systems was discussed. Photorefractive effect of photorefractive materials containing different nonlinear chromophore and photorefractive matrix was compared, which have helped the research of carbazole doped photorefractive materials.N-bromobutane was synthesized by sulfur-bromine method. The optimal conditions were as follows: volume ratio between bromine and alcohol was 0.25~0.3:1, volume ratio between water and alcohol was 0.17~0.35:1, reaction was refluxing for 7h, previous reaction temperature was 40℃, middle reaction temperature was 100℃and distillation temperature was 100~103℃. Yield of products was 93.1% under this condition. The samples were characterized by means of melting points and refraction coefficients. The results showed that this product was n-bromobutane.Two nonlinear chromophore containing azo group, BDMNPAB and DMNPAA, were synthesized with n-bromobutane, methyl bromide, 2,5- dimethylphenol, 4-nitroaniline and sodium nitrite. The samples were characterized by means of FTIR, UV-vis, XRD and melting points. Two-beam coupling gain coefficients of photorefractive systems using PVK or PVK-azo as matrixes were measured by two-beam coupling experiment. The experiment showed diffraction spot after laser irradiation, which indicated that sample had photorefractive effect. Effect of mass fraction of NLO in photorefractive systems on photorefractive properties was studied at electric field of 4V/μm, temperature of 50℃, angle between incident light and normal line of 30°and angle between two incident light of 30°. The results indicated that the greatest two-beam coupling gain coefficients were 6.9cm-1, 7.5cm-1 and 8.4cm-1 respectively when PVK:DMNPAA:TNF, PVK:BDMNPAB:TNF, PVK-azo:BDMNPAB:TNF. Two-beam coupling gain coefficients of photorefractive materials using PVK-azo as matrix were higher than that using PVK as matrix in the photorefractive materials of same composition.The relationship between two-beam coupling gain coefficients of photorefractive systems using PVK or PVK-azo as matrixes and electric field was studied. The results showed that two-beam coupling gain coefficients was increased with the increasing of electric field.The relationship between two-beam coupling gain coefficients of photorefractive systems using PVK-azo as matrixes and mole fraction of azo nitrobenzene was studied. The results showed that two-beam coupling gain coefficients was increased with the increasing of mole fraction of azo nitrobenzene at electric field of 4V/μm, temperature of 50℃, angle between incident light and normal line of 30°and angle between two incident light of 30°.