LiNbO_3中光折变全息的热固定特性  

Characters of Recording and Thermal Fixing in Lithium Niobate

作　　者：刘波[1] 刘立人[1] 徐良瑛[2] 

机构地区：[1]中国科学院上海光学精密机械研究所 [2]中国科学院上海硅酸盐研究所

出　　处：《光学学报》1999年第7期941-947,共7页Acta Optica Sinica

基　　金：国家自然科学基金;上海应用物理中心资助课题

摘　　要：带输运模型方程和耦合波方程结合起来研究ＬｉＮｂＯ３晶体中体全息记录和热固定的特性。发现在一边记录一边固定时，同时存在的离子光栅通过减小耦合增益而影响了电子光栅的写入，且得到的固定后折射率光栅随深度的改变较小，这与记录完固定有非常大的区别。两种热固定方法得到的折射率光栅的衍射效率大小将主要决定于入射记录光的初始光强比。该模型同时显示对于高掺杂浓度的ＬｉＮｂＯ３晶体的热固定，在其显影过程中，由于导带电子有很大的弛豫率，因而无法擦除其中的电子光栅，这样得到的折射率光栅将只有很低的衍射效率。A theoretical model, in which the band transport equations and the coupled wave equations are both considered, to describe the characters of recording and thermal fixing in LiNbO 3 is presented. It is found that in simultaneous fixing, the existing ionic grating affect the writing of the electronics grating by reducing the coupling gain and the grating envelope of the fixed index grating by simultaneous fixing is quite uniform inside the photorefractive crystal with comparison to by post fixing. The resulting diffraction efficiency of the fixed volume grating is mainly dependent on the initial intensity modulation of the two writing beams. The model also shows that fixing in a high doped material, at its developing stage, the electric grating can not be erased which resulting in low diffraction efficiency. A set of experimental demonstration are presented.

关 键 词：光折变全息 热固定 耦合波 铌酸锂 

分 类 号：O438[机械工程—光学工程] O734.1[理学—光学]