涂层圆柱光波导传光特性的研究

研究了一种双包层阶跃型光纤，涂层作为内包层，其折射率大于纤芯及外包层的折射率。严格地推导了柱坐标下的特征方程。并在两种极限情况下，推广到平板光波导和传统的阶跃型光纤。详细计算了ＴＭ和ＴＥ波的场分布及功率分布，做出了相应的曲线，表明了涂层厚度和工作波长对场及功率分布的影响。

Study of Propagation Characterstic in a Coating Cylindrical Optieal Waveugide

A theoretical study is made in a step index optical fiber of the doubly calds. The inner clad which is a coating has a higher refractive index than the core and the outer clad. In a polar corrdinate, the mode equation is obtained exactly, which can become into the mode equations of a conventional single clad step index fiber and a planar slab at two extreme specieal cases. In the paper, the electric filed distribution and the power distribution inside the core and the coating for TE mode and TM mode are calculated and the curves relating to the calculation results are given. It is shown that the electric field distribution and the propagating power distribution are influenced remarkably by the thickness of the coating and the wavelength.