Ce∶KNSBN光折变类光纤简并四波混频特性研究

Properties of Degenerate Four-Wave Mixing with Ce∶KNSBN Photorefractive Fiber-Like Crystal

研究了Ce∶KNSBN光折变类光纤在泵浦光和信号光夹角分别为小角度和大角度两种情况下简并四波混频的基本特性 .当夹角较大时 ,在光折变类光纤内部形成了两个四波混频作用区域 ,获得了比小角度情况提高 4倍的大相位共轭反射率 .给出了Ce∶KNSBN光折变类光纤中 ,在入射夹角分别为小角度和大角度两种情况下 ,相位共轭光反射率分别随信号光光强、两束泵浦光光强比变化的实验结果 ,并用理论公式进行了拟合 ,理论分析和实验结果相符 .还研究了Ce∶KNSBN光折变类光纤四波混频光栅模式和相位共轭光时间响应特性 .光折变类光纤的相位共轭响应时间较快 ,可为秒量级 .

Properties of degenerate four wave mixing in a Ce∶KNSBN photorefractive fiber-like crystal in the conditions that the angle between the pump beam and the signal beam is small and large are studied. It is found that there are two interaction regions of degenerate four-wave mixing in the sample when the angle is large, and four-time enhancement of the maximum phase-conjugate reflectivity compared with that in small angle condition is obtained. The experimental results of the phase-conjugate reflectivity versus the intensity of signal beams, and versus the ratio of the pump beams are presented, which are numerically fitted by theoretical equations. They are coincident quite well. The property of the four-wave mixing gratings and the phase-conjugate response time of Ce∶KNSBN photorefractive fiber-like crystal were studied. The response time could be faster, in an order of second.