Cr:KNSBN光折变晶体非简并四波混频特性

Nondegenerate Four-Wave Mixing of Cr:KNSBN

应用波长为514.5nm的Ar+离子激光和波长为632.8nm的He-Ne激光对Cr:KNSBN光折变晶体的非简并四波混频特性进行了实验研究.测量了相位共轭光的时间变化过程,相位共轭反射率随信号光与前向泵浦光夹角的关系,相位共轭反射率与泵-泵比的关系及相位共轭反射率与信-泵比的关系.实验发现,当信号光与前向泵浦光的夹角为21°、泵-泵比为0.36时可获得最大的相位共轭反射率30%.利用相应的光折变理论对相位共轭反射率与泵-泵比、相位共轭反射率与信-泵比的关系进行了数值拟合,数值计算结果与实验测量结果有较好的吻合.该项研究为Cr:KNSBN晶体在图像变换、彩色相位共轭和波前整形等领域的应用提供了实验依据.

Using Ar^＋ laser of 514.5 run as the signal beam and the pump beam, and He-Ne laser of 632.8 nm as another pump beam, the nondegenerate four-wave mixing（NFMW） was realized in the Cr： KNSBN.The time evolution of the frequency-varied phase conjugate wave intensity, the dependence of the phase conjugate refleetivity on the incident beams, the dependence of the phase conjugate refleetivity on pump-to-pump ratio, and the dependence of the phase conjugate refleetivity on signal-to-pump ratio were investigated. At the condi- tions of the angle 21^o between the pump beam and the signal beam, and pump-to-pump ratio 0.36, the maxi- mum conjugate refleetivity 30 % was obtained. The relationships between the phase conjugate refleetivity and pump-to-pump ratio, signal-to-pump ratio were numerically fitted by corresponding photofractive theory, and calculating results and experimental results were coincident quite well. This research gives a significant support to the applications of Cr： KNSBN crystal in image transformation, color image phase conjugate and wavefront correction.