EMUstack: an open source route to insightful electromagnetic computation via the Bloch mode scattering matrix method

We describe EMUstack, an open-source implementation of the Scattering Matrix Method (SMM) for solving field problems in layered media. The fields inside nanostructured layers are described in terms of Bloch modes that are found using the Finite Element Method (FEM). Direct access to these modes allows the physical intuition of thin film optics to be extended to complex structures. The combination of the SMM and the FEM makes EMUstack ideally suited for studying lossy, high-index contrast structures, which challenge conventional SMMs.本文介绍了EMUstack——一款用于求解分层介质中场问题的散射矩阵法（Scattering Matrix Method, SMM）的开源实现。纳米结构层内的场以布洛赫模式（Bloch modes）进行描述，该模式通过有限元法（Finite Element Method, FEM）求解得到。直接获取此类模式，可将薄膜光学的物理直观拓展至复杂光学结构。散射矩阵法与有限元法的结合，使得EMUstack特别适用于研究有损、高折射率对比度结构——这类结构对传统散射矩阵法构成了挑战。