写入光偏振态对Ce：KNSBN晶体衍射特性的影响

Effect of Writing Beam Polarization State on Diffraction Property of Ce:KNSBN Crystal

采用非同时读出条件下晶体两波耦合实验装置,以单束光入射Ce:KNSBN光折变晶体,通过改变抽运光偏振方向和晶体c轴的夹角φ,系统记录了不同φ角下的抽运光透射光强I′p随时间的变化情况。实验结果表明,当φ≤30°时,基本没有光扇效应;实验研究了正交偏振光写入下Ce:KNSBN晶体的两波耦合动态过程,并与e光写入下两波耦合动态过程进行了比较,发现正交偏振光写入时光扇噪声得到了明显抑制,在相同的写入参量条件下光栅的衍射效率明显提高。

With single pump beam incident in Ce：KNSBN, the temporal evolution of transmission intensity of pumping beam in Ce： KNSBN crystal is experimentally studied by altering the angle φ between the polarizing orientation of the pump beam and c axis of the crystal. The experiment is carried out on crystal two-wave-coupling experimental setup with non-synchronous readout. The results show that the beam fanning noise is little at φ≤30°. The two-wave coupling is investigated in Ce：KNSBN crystal with orthogonally polarized waves. Compared with the situation of extraordinary polarization, the beam fanning noise is effectively suppressed, and the diffraction efficiency of volume grating is greatly improved.