弯曲光波导的本地场理论

本文从弯曲光波导的本地正交弯曲坐标系出发,展开MaxweII方程组,并借助于函数变换和普通小参数展开法导出了在o(1/R)近似下的弯曲光波导的修正场本地方程及修正传播常数。以圆光纤为例,讨论了一阶近似本地场形式及基模场在最大值处的场位移。与一些文献作以比较,我们的计算与数值方法相一致。本理论的特点是利用相应直波导的已知场来构造弯曲光波导的本地场,故本理论适应于分析任意截面,亦满足于在弱导条件下的弯曲光波导。

LOCAL FIELD THEORY OF BENT OPTICAL WAVEGUIDE

Basing on the local orthogonal curved co-ordinate systems,this paper expands the Maxwell's equations and obtains the perturbation correction local field equations and propagation constants in the bent optical waveguides by making use of the field function tarnsformations and the singular Perturbation expansion method. Taking the circular fibres for the example, the first order correction local field and field shift in the fundamental mode peak field are discussed. Our results are in good agreement with the numerical results.It is noted that according to the local field theory, any local fields of bent optical waveguide with any shape of the crosssection can be composited of the field of unperturbed straight optical waveguuide, but this theory is limited to the weakly-guiding optical waveguides.