5层金属包覆介质波导的模式特性研究

Modal Characteristics Study of 5-layer Metal-clad Waveguide

采用有限元方法(FEM)对具有复折射率的金属包覆5层平板波导和矩形波导的折射率及模场分布进行了求解并进行了定性的分析,得到了5层平板波导的模折射率随芯层厚度、缓冲层厚度和金属层厚度的变化关系;给出了等离子体表面模的模场分布演变,揭示了在缓冲层变化时等离子体表面波向普通TM模式及低阶TM模向高阶TM模的演变过程;计算了二维结构5层矩形波导的模折射率随缓冲层厚度、芯层厚度和芯层宽的变化关系。结果表明,在二维结构的金属包覆波导中存在多种等离子体表面模,在缓冲层的变化过程中其TM模同样存在模式转变过程,并给出了部分等离子体表面模的模场分布;在金属层的影响下,TM模式的模场分布受到扰动,并给出了受扰动的低阶TM模的模场分布。

Mode refractive index and mode field distribution of metal-clad 5-layer slab waveguide and rectangular waveguide were investigated by finite element method. The dependence of mode refractive index on thickness of core layer, buffer layer and metal layer of slab waveguide and thickness of buffer layer and core layer, and width of core layer of rectangular waveguide was calculated respectively. The phenomena of TM mode evolution during the variation of the thickness of buffer layers was observed. Multiple plasma surface modes were observed in 2-dimensional rectangular waveguide. Mode field distribution during the cause of mode evolution of slab waveguide and that of plasma surface mode of rectangular waveguide were given.