运用耦合方程,分析了在轴向应力作用下弱导圆光纤及矩形波导中的耦合行为.结果表明,由于弱导光纤中的模场分布在角向具有特定的函数形式,轴向应力不会引起简并模式间的耦合,而只会导致失谐,但对于矩形波导,轴向应力不仅导致失谐,并且会引起具有相同偏振态的简并模式间的耦合.得出了两模矩形波导的长宽比越小,波长越长,其由于轴向应力引起的模内双折射就越大的结论.

We have investigated the axially strained weakly guiding optical waveguides using mode-coupling equation. The results show that the less is the ratio of length to broad of retangular guide and the longer is the wavelength, the higher is the axialstraininduced birefringence between orthogonal polarizations.