Theoretical and experimental investigation on the applied electric field-and intensity-dependent photorefractive response in a photorefractive polymeric composite is presented.The decay time constant and the correspon...Theoretical and experimental investigation on the applied electric field-and intensity-dependent photorefractive response in a photorefractive polymeric composite is presented.The decay time constant and the corresponding grating-amplitude for the composite consisting of 1-n-butoxy1-2,5-dimethy1-4-(4’-nitrophenylazo)benzene:poly(N-vinylcarbazole):2,4,7-trinitro-9-fluorenone with a weight ratio 44:55:1 were measured.The results revealed that there existed two gratings simultaneously,one was caused by the photorefractive effect,and the other was contributed from the photo-isomerization process.The dynamic process for the photorefractive grating was explained with a modified band transport model.展开更多
Anomalous long-time increase of the diffraction efficiency is observed in dark-decay experiments of photorefractive gratings in Ce：BaTiO3. It is deduced that a phase-conjugate beam is induced by the writing beam at a...Anomalous long-time increase of the diffraction efficiency is observed in dark-decay experiments of photorefractive gratings in Ce：BaTiO3. It is deduced that a phase-conjugate beam is induced by the writing beam at acute angle to the ＋c axis of the crystal and it interferes with the other writing beam to form a second grating which is perpendicular to the first grating formed by the interference between two writing beams. The rising behaviour of the diffraction efficiency results from the different decay rates of these two photorefractive gratings. Furthermore, a simplified model of two gratings, both induced by two deep traps, is proposed to account for this phenomenon and the fitting results agree well with the experimental results.展开更多
The principle of fiber Bragg gratings(FBG) is briefly described. The formation technologies of FBG are systematically given and analyzed. In addition, the experiment is described in detail, e.g.,the phase mask method ...The principle of fiber Bragg gratings(FBG) is briefly described. The formation technologies of FBG are systematically given and analyzed. In addition, the experiment is described in detail, e.g.,the phase mask method is used to write directly the period Bragg gratings into the Ge-doped single mode fiber with KrF excimer UV laser. The results of experiment are also presented and analyzed.展开更多
基金Supported by the Science Foundation of the Post-Doctor of China,National Natural Science Foundations of China under Grant No.19525412State Science and Technology Commission of China.
文摘Theoretical and experimental investigation on the applied electric field-and intensity-dependent photorefractive response in a photorefractive polymeric composite is presented.The decay time constant and the corresponding grating-amplitude for the composite consisting of 1-n-butoxy1-2,5-dimethy1-4-(4’-nitrophenylazo)benzene:poly(N-vinylcarbazole):2,4,7-trinitro-9-fluorenone with a weight ratio 44:55:1 were measured.The results revealed that there existed two gratings simultaneously,one was caused by the photorefractive effect,and the other was contributed from the photo-isomerization process.The dynamic process for the photorefractive grating was explained with a modified band transport model.
基金Project supported by the National Natural Science Foundation of China （Grant No 60078002）,
文摘Anomalous long-time increase of the diffraction efficiency is observed in dark-decay experiments of photorefractive gratings in Ce：BaTiO3. It is deduced that a phase-conjugate beam is induced by the writing beam at acute angle to the ＋c axis of the crystal and it interferes with the other writing beam to form a second grating which is perpendicular to the first grating formed by the interference between two writing beams. The rising behaviour of the diffraction efficiency results from the different decay rates of these two photorefractive gratings. Furthermore, a simplified model of two gratings, both induced by two deep traps, is proposed to account for this phenomenon and the fitting results agree well with the experimental results.
文摘The principle of fiber Bragg gratings(FBG) is briefly described. The formation technologies of FBG are systematically given and analyzed. In addition, the experiment is described in detail, e.g.,the phase mask method is used to write directly the period Bragg gratings into the Ge-doped single mode fiber with KrF excimer UV laser. The results of experiment are also presented and analyzed.
