光纤声光互作用耦合波方程

Coupled-wave Equations of Fiber Acousto-optic Interaction

从参量互作用基本方程出发,导出微扰形式的光纤耦合模方程;视超声波为微扰,推导出光纤声光互作用耦合波方程组,它包括前向波和后向波两个方程．通过求解耦合波方程组,得到后向波效率计算公式,并证明在弱声光互作用的条件下,后向波的光强与超声波功率近似成正比．该研究为光纤声光强度调制器的研制打下了理论基础,这种新型调制器将在光纤通信领域中有广泛的应用前景．

A fiber coupled-mode equation with perturbation is given from basic equation of the parameter interaction. Considering ultrasonic wave as perturbation, a coupled-wave equation group of fiber acousto-optic interaction is deduced. This equation group includes equations of forward wave and backward wave. The equation group is a theory base of fiber acousto-optic effect. Through solving the equation group, a formula of backward wave efficiency is obtained. It is proved that under condition of weak acousto-optic interaction, the intensity of the backward wave is directly proportional to acoustic power approximately. The research in this paper will lay theoretical foundation on manufacture of the fiber acousto-optic intensity modulator. The new modulator can be widely applied to optical fiber communication.