The Spectral Numerical Mode Matching Method for Simulating Concentric All-Fiber Sensor Structures With Metallic Films

The concentric all-fiber structures have attracted extensive attention because of their promising applications. However, the reflection, transmission spectrum, and electromagnetic (EM) fields in such fibers cannot be accurately calculated by using the traditional methods, because these models are long, and the metallic films embedded in these fibers are highly conductive. In this work, the spectral numerical mode matching (SNMM) method is developed to address these challenges directly from a 2.5-D perspective. The absorbing boundary condition (ABC) is introduced into the mixed spectral element method (MSEM) to truncate the open fibers in the transverse directions. The surface current boundary condition (SCBC) is used to approximate the original metallic films so that the SNMM can improve computation speed by avoiding fine meshes. Several numerical simulations are carried out to show the validity, accuracy, and advantages of the proposed method.