无偏置交流电场下向列液晶中的耦合增益特性  

Coupling Properties in Nematic Liquid Crystal under Nonbiased Alternating Electric Field

作　　者：裴延波[1] 姚凤凤[1] 孙秀冬[1] 

机构地区：[1]哈尔滨工业大学物理系,黑龙江哈尔滨150001

出　　处：《光学学报》2009年第12期3494-3497,共4页Acta Optica Sinica

基　　金：哈尔滨工业大学科研创新基金(HIT.NSRIF200802)资助课题

摘　　要：用交流电场代替直流电场来驱动液晶光折变器件能够克服直流电场带来的动态散射、永久光栅、电解等效应,这些对于器件的实用是非常不利的。利用二波耦合方法在无偏置正弦交流电场作用下研究了掺C60的向列液晶中记录的光折变光栅的形成及其相干放大应用。实验中在交流电场作用下于通常的、掺C60的向列液晶盒中观察到了稳定的非对称能量转移,并获得了和直流电场下相比拟的、大的光束耦合比,从而证明在交流电场下液晶薄膜中记录的光栅是由光致空间电荷场作用下的液晶分子重新取向而形成的。利用上述强的光束耦合比实现了交流电场作用下的相干放大实验,并在小的输入光强下取得了190 cm-1的增益。Driving liquid crystal photorefractive devices with an alternating electric field instead of the dc electric field can overcome some disadvantages induced by the use of the dc electric field, such as the dynamic scattering, permanent grating, and electrolyte. The formation and the application of coherent amplification of gratings recorded in C60-doped nematic liquid crystal under nonbiased sinusoidal alternative electric field were investigated by using two-beam-coupling experiment. Stable asymmetric energy transfer between two writing beams was observed in this kind of cell, indicating the photorefractive nature of the grating recording in nematic sample under the ac electric field. Large beam-coupling ratio was obtained, and the value was compared with that at adc electric field. Finally the coherent amplification was realized, and the gain coefficient as high as 190 cm^-1 was achieved.

关 键 词：非线性光学 相干放大 二波耦合 向列液晶 全息术 

分 类 号：O753.2[理学—晶体学]