在局域响应的光折变晶体中的相干光放大

COHERENT LIGHT AMPLIFICATION IN PHOTOREFRACTIVE CRYSTALS WITH A LOCAL RESPONSE

理论和实验表明，在由光生伏打电荷迁移为主的局域非线性响应的薄光折变晶体（ＬｉＮｂＯ３∶Ｆｅ）中实现弱信号光放大是可能的．光能流从抽运光向信号光不可逆转移的起因是两束入射光与背面反射光之间的四波作用形成互倾斜、彼此有一定空间相移的两组相位栅．当入射抽运光在非布喇格条件下读出由反射光和其衍射光所写入的新光栅时，弱信号便获得相干放大．对理论计算与实验结果进行了比较．

It is shown theoretically and experimentally that a weak signal light amplification is possible in thin photorefractive crystals with a local nonlinear response due to photovoltaic charge transport.The origin of the power exchange is that four wave interaction of the input beams and reflection beam at the rear will form two sets of bending gratings with certain spatial phase shift.When the grating written by the reflection wave and its diffracted wave is read by the input pump beam under off Bragg condition ,the weak signal beam achieves coherent amplification.Theoretical and experimental results are compared with each other.