磁光薄膜波导中光导波的模式转换和衍射效率计算

Calculations on the Efficiecies of Modeconversion and the Diffraction of Guided Optical Waves with Magnetostatic Waves in Bidoped YIG Film

根据耦合模理论，应用微扰方法分析了Ｂｉ：ＹＩＧ薄膜波导中斜向静磁场对静磁波与导波光相互作用的影响，计算了斯托克斯（Ｓｔｏｋｅｓ）和反斯托克斯（ａｎｔｉ－Ｓｔｏｋｅｓ）相互作用中导波光的模式转换效率和衍射效率。计算结果表明，仅当垂直磁化时，导波光的模式转换效率才与衍射效率在数值上相等；利用高比法拉第旋转的Ｂｉ：ＹＩＧ薄膜以及适当的斜向场，可大幅度提高导波光模式转换效率和衍射效率；在一定的斜向场范围内（倾斜角θ＞４°），斯托克斯和反斯托克斯相互作用的衍射效率基本相等，对于模式转换效率，也有同样的结论。

According to the coupledmode theory,the effect of bias inclined magnetic field on the interaction of guided optical waves and magnetostatic waves in the Bi:YIG film waveguide is analyzed by means of the perturbation method.The diffraction efficiency(DE) and the modeconversion efficiency(MCE) in the Stokes and antiStokes interactions are calculated.Calculation results indicate that,only at normal magnetization,the MCE and the DE are equal in magnitude;under appropriately inclined magnetic field,both the MCE and the DE in the Bi:YIG film can be increased by a big margin;when the inclined angle >4,the DE (or the MCE) in the Stokes interaction is basically equal to that in the antiStokes interaction.