基于弱耦合模理论的空间多波导耦合特性研究

不在同一平面的空间多波导中光耦合发生在横截面两个方向,利用空间多波导可以方便、有效地实现不同层间器件的互连。将平面波导耦合模理论推广到空间多波导之间的耦合,在弱导引条件下给出了空间多波导的耦合方程。利用该耦合方程对三维集成光学器件中常见的空间三波导和空间四波导的耦合特性进行分析,得出光强分布及耦合长度的解析表达式,并用三维全矢量光束传输法验证了分析结果。分析结果表明利用空间多波导可以实现水平和垂直两个方向上的均匀或非均匀分束,为利用空间多波导之间相互耦合的三维定向耦合器件的设计和分析提供理论基础。

Characteristic Analysis of Spatial Multiwaveguide System Based on Weakly Coupled-Mode Theory

The coupling among waveguides on different planes occurs in both transverse and vertical directions.Using the spatial multiwaveguide system,we can interconnect devices in different layers effectively.Based on the weakly coupled-mode theory,the planar waveguide coupling theory is generalized to spatial multiwaveguide system,and the coupled-mode equations of the spatial multiwaveguide system are presented.As an application example,the coupled-mode equation is applied to analyze the coupling properties in spatial three-and four-waveguide systems.The analytical expressions of light intensity distributions and coupling length in the two specific cases are given,and the three-dimensional full-vector beam propagation method is used to verify the analytical results.The analysis result shows that the spatial multiwaveguide system permits uniform and nonuniform power splitting in two orthogonal directions.These analytical formulas are useful in designing three-dimensional directional couplers,which is based on spatial multiwaveguide coupling.