【摘要】 提出一种新型的分析多模光纤光栅的准三维时域有限差分束传播法(Q-3D-FDTD-BPM).在圆柱坐标系下将场在角向分量的解析式分离出来,使三维方程变为若干个二维方程求解,从而简化了三维离散化方程.同时使用综合道格拉斯(GD)法和交替隐向迭代法(ADIM),获得比中心差分算子高两个数量级的空间离散精度.然后根据场强加权转换方案,加权综合各子方程解,从而得到多模光纤中三维场解.基于这种方法,模拟多模光纤光栅中场分布,得到与实验结果多模式特性基本一致的光栅传输光谱图.更多还原

【Abstract】 In this paper, a novel quasi-three-dimensional finite-difference time-domain beam propagation method(Q-FDTD-BPM) is proposed. In the cylindrical coordinate, the azimuthal component of the vector field solution is separated and three-dimensional equation is decomposed into several two-dimensional equations, which simplify the 3D discrete equations. And the method presented is developed using an alternating-direction implicit method and generalized Douglas scheme,which achieves higher accuracy than the regular FD scheme. Next the transform scheme is used to obtain the 3D resolutions of the equation. Based on this method, the simulated results for the spectrum of MMFG is obtained with a good approximation to the results in the experiment.更多还原