研究了Co:KNSBN晶体和重还原Co:KNSBN晶体中光致吸收的变化特性。Co:KNSBN晶体的吸收系数随泵浦光强的增加而减小,吸收系数变化的最大值为3.2 cm-1,重还原Co:KNSBN晶体的吸收系数随泵浦光强的增加而增加,吸收系数变化的最大值为6.5 cm-1,在泵浦光关掉后,探测光频率很高的增幅振荡,然后呈现阻尼振荡。采用最近建立的双载流子(电子,空穴)和多重陷阱能级(两个深陷阱能级,两个浅陷阱能级)的光折变理论给以合理的解释,同时指出晶体的光致吸收变化特性在获得空间均匀光和非相干光放大中,有着潜在的应用。

Intensity dependent absorption in doped KNSBN crystals have been studied. Light induced absorption and transparency in Co:KNSBN and heavy reduced Co:KNSBN have been experimentally measured. Light induced absorption increases and reaches a saturate value of 6.5 cm -1 in heavy reduced Co:KNSBN crystal. Light induced absorption decreases and reaches a saturate value of 3.2 cm -1 in Co:KNSBN crystal. The transparent intensity of probe beam present a oscillation behavior when the pump beam switch off in heavy reduced Co:KNSBN crystal. These behaviors are explained by a theory of two types of charge carriers with multiple traps. Finally, we predict that the light induced absorption and transparency should be useful for making spatial intensity distributions more homogeneous and incoherent signal amplification.