交变磁场下法拉第效应研究

The Faraday Effect in the Alternating Magnetic Field

介绍了交变法拉第效应的磁光调制测量原理和方法，分析了亚铁磁性材料法拉第Ｆｒａｄａｙ效应和磁光调制深度与交变磁场频率间的关系，证明了交变法拉第旋转幅值θ０的实部θ＇０小于静磁场下的θ＇ｓ，而虚部θ″０大于θ″ｓ，理论和实验结果相吻合。由此得出结论，采用具有磁圆二向色性的磁光材料做成的调制器不可能达到彻底的开关状态。

The principle and method of the magneto-optical modulation measuring the Faraday effect in a sine magnetic field have been proposed. A theoretical analysis has been performed on the magnetic field-frequency dependence of both the Faraday effect and the degree of the magneto-optical modulation in ferrimagnetic medium.It has been shown that θ',the real part of the Faraday rotation θ,in an alternating magnetic field is smaller than that in a static field, while the imaginary part θ″is larger than that in a static field.The theory corresponds with the experimental results.The conclusion has been drawn that it is imposible to realize complete on-off switch by a modulator utilizing magneto-optical materials with magnetic circular dichroism.