斜向静磁场中光导波模式转换与衍射理论

THEORY OF GUIDED WAVE MAGNETOOPTIC BRAGG DIFFRACTION IN YIG GGG WAVEGUIDE UNDER INCLINED BIAS MAGNETIC FIELD *

应用经典场论和耦合模理论计算了斜向静磁场作用下，磁性薄膜波导中静磁波与导波光的相互作用．计算结果表明，与垂直静磁场情形相比，斜向静磁场时的相匹配条件有所变化，由于磁性薄膜波导中法拉第磁光效应增强等因素，导波光的Ｂｒａｇｇ衍射效率得以显著增加．这有利于应用ＹＩＧ等低损耗磁性薄膜做成高衍射效率的磁光波导器件，亦有利于降低Ｂｉ∶ＹＩＧ等高比法拉第旋转的磁光薄膜波导器件的体积和损耗．此外，理论指出的在斜向静磁场条件下所具有的一些磁光特性与实验结果亦符合得很好．

Abstract A theoretical Treatment is presented on the propagation characteristics of magnetostatic forward volume waves and related guided wave magnetooptic (MO) Bragg diffraction in an YIG GGG waveguide under an inclined bias magnetic field.It is found that,in contrast to the usual situation of a perpendicular bias magnetic field,an inclined bias magnetic field leads to the modification to the phase matching condition and,as a result of increased Faraday effect etc.,facilitates enhancement of MO Bragg diffraction efficiency.Such an efficiency enhancement enables utilization of low propagation loss materials such as the pure YIG for construction of viable guided wave MO Bragg devices.The theoretical predictions are in good agreement with the experimental results.