短脉冲光在光伏光折变晶体中写入和擦除光折变光栅理论研究  

Theoretical Study on Writing and Erasing of Gratings in Photovoltaic Photorefractive Crystal with Short Light Pulses

作　　者：杨冰[1] 阎晓娜[2] 路灿云[1] 

机构地区：[1]聊城大学物理科学与信息工程学院,山东聊城252059 [2]上海大学理学院物理系,上海200444

出　　处：《光子学报》2010年第2期214-218,共5页Acta Photonica Sinica

基　　金：国家自然科学基金(60377017;60571062);上海市重点学科基金(T0104);聊城大学科研基金(X061017)资助

摘　　要：利用GC Valley的准连续光(Quasi-cw)近似模型,研究了短脉冲激光(纳秒ns量级)在光伏光折变材料LiNbO3晶体中写入和擦除光折变光栅的过程,给出了空间电荷场随时间变化的表达式.理论研究表明,空间电荷场的形成和擦除与两个时间参量有关,在考虑或者不考虑光生伏打效应两种情况下,这两个参量随擦除光强的变化有基本相同的变化规律,光栅的写入和擦除有相同的结果.同样,擦除一个光栅所需的光能量在两种情况下也有相同的结果.因此,在短脉冲光入射光折变晶体材料情况下,考虑光生伏打效应与不考虑光伏效应,对短脉冲光在光折变LiNbO3晶体中写入和擦除光栅基本没有影响.Based on Valley＇ s quasi-cw approximation, the writing and erasing of gratings in materials exhibiting bulk photovoltaic effect on illumination with short light pulses （such as ns pulses） is investigated. The expression of space-charge field is given out in the paper with two time constants τpa and τpb. When considering and not considering the photovoltaic effect,the diagrams of the two time constants as a function of irradiance in units of 1/（SτR） are the same. The energy required to erase a grating to 1/e of its initial value is also studied in the two cases and the two results are also the same. In the case of short light pulses irradiance,photovoltaic effect has no effect on the writing and erasing photorefractive gratings in the LiNbO3 crystal.

关 键 词：非线性光学 光折变效应 光伏效应 光栅 准连续光近似 空间电荷场 

分 类 号：O436.1[机械工程—光学工程]