Anomalous behaviour of long-time increase in diffraction efficiency of photorefractive grating in Ce：BaTiO3 in dark  

作　　者：张嘉文 张明 徐英 洪治 

机构地区：[1]Centre for Optical and Electromagnetic Research, State Key Laboratory of Modern Optical instrumentation [2]Zhejiang Provincial Key Lab Zhejiang University, Hangzhou 310027, China of Optic Fiber Communication Technology, Zhejiang University of Technology, Hangzhou 310032, China

出　　处：《Chinese Physics B》2006年第4期729-734,共6页中国物理B（英文版）

基　　金：Project supported by the National Natural Science Foundation of China （Grant No 60078002）,

摘　　要：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.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.

关 键 词：dark decay photorefractive grating two deep-trap model Ce：BaTiO3 

分 类 号：O436[机械工程—光学工程]