Ce∶BaTiO_3中光折变光栅衍射效率上升现象及分析  

Behaviors and Analysis of Diffraction-Efficiency Ascending of Photorefractive Grating in Ce∶BaTiO_3

作　　者：张明[1] 洪治[2] 张嘉文[2] 

机构地区：[1]浙江工业大学理学院,杭州310023 [2]浙江大学现代光学仪器国家重点实验室光及电磁波研究中心,杭州310027

出　　处：《光子学报》2007年第4期609-612,共4页Acta Photonica Sinica

基　　金：国家自然科学基金(60078002);浙江大学现代光学仪器国家重点实验室开放课题(LMOI-0407)资助

摘　　要：在对Ce∶BaTi O3晶体进行双光束干涉光折变光栅暗衰减特性的实验研究中,发现了暗条件下光折变光栅归一化衍射效率长时间上升的异常现象:在e光偏振、大入射角度产生光折变光栅的实验中,衍射效率在长逾8 h的时间内持续上升.而在e光干涉、小入射角度和o光干涉时均未出现衍射效率长时间上升的现象.分析认为:由于自泵浦位相共轭光的产生和晶体中的两个深能级参与了光折变过程,形成了衰减速度不同、光栅方向垂直的两个光栅,导致了暗衰减时衍射效率的长时间上升.　Anomalous long-time ascending of the diffraction efficiency is observed in dark-decay experiments of photorefractive gratings formed by interference of two writing beams in Ce∶BaTiO3. In the experiments with e-polarized and larger-angle writing beams, the diffraction efficiency kept rising over 8 hours. The diffraction efficiency, however, did not exhibit rising behaviors in the experiments of both epolarized with smaller angle and o-polarized. It is deduced that the forming of two mutually perpendicular gratings with different decay rates and the long-time diffraction-efficiency ascending are caused by the selfpumped phase-conjugate beam and two deep traps involved in the photorefractive grating.

关 键 词：非线性光学 暗衰减 光折变光栅 Ce:BaTiO3 

分 类 号：O734.1[理学—晶体学]