磁光光纤Bragg光栅中圆偏振光的非线性传输特性

提出了磁光光纤Bragg光栅的理论模型，给出了圆偏振光在磁光光纤光栅中传播的非线性耦合模方程. 研究表明，在磁光光纤Bragg光栅中，光栅引起正反传播方向的导波光发生耦合，法拉第效应引起磁圆双折射效应，而非线性效应则将左旋和右旋圆偏振光耦合在一起，它们的共同作用可使双稳态状态发生反转、非线性光控光开关阈值功率降低. 与传统光纤光栅相比，利用左旋和右旋磁圆偏振光之间的交叉相位调制实现的脉冲整形具有磁光偏置可调特性，为基于磁光光纤光栅的动态灵活全光3R再生器的研制提供了理论基础. 关键词： 磁光光纤Bragg光栅 圆偏振光 脉冲整形

Nonlinear propagation of circularly polarized light in magneto-optic fiber Bragg gratings

The theoretical model of magneto-optic fiber Bragg gratings （MFBG） is proposed and the nonlinear coupled-mode equations for circularly polarized light in MFBG is derived for the first time. Our analysis shows that the coupling between right- and left-handed circularly polarized light along with the magnetically circular birefringence （the Faraday effect） resulting from the nonlinear effects and the grating structure is responsible for the coupling of forward and backward guided optical waves with identical states of polarization. In the MFBGs, the reversal of transmission characteristics and lower power threshold of nonlinear bistable switching can be achieved under appropriate magneto-optic bias. The MFBG-based pulse reshaping scheme by utilizing cross-phase modulation （XPM） of right- and left-handed circularly polarized light has a great advantage in magnetic adjustability over that based on conventional fiber gratings and is useful for the development of dynamically controllable all-optical 3R regenerators.