Boundary element analysis of polarization holding fibers

The boundary element method has drawn wide attention as a novel numerical method of the boundary integration equation, and it has already been applied to the electromagnetic initial value problems. In this paper, we apply the boundary element method to the electromagnetic wave eigenvalue problems and establish a numerical method which is applicable to analyze the guided modes of waveguides with arbitrary structure. Then as an application example of the present method, we make numerical calculation of the elliptical core optical fiber, which is the typical polarization holding optical fiber, and clarify the cutoff frequencies of the first‐ and second‐order higher modes of the fiber. Also, the propagation constant and the geometrical anisotropy of the fundamental mode of the fiber are obtained. Again, the maximum anisotropy of the elliptical core fiber is shown to be obtained for the normalized frequency of 1.85 and ellipse factor of the core equal to 0.8. From these results we conclude that the boundary element method has high accuracy of calculation, is easy to apply, and has highly stable solution.