Approximate vector analysis of single‐mode optical fibers with arbitrary refractive index distribution

The single‐mode optical fiber, which has stable polarization characteristics, is one of the most important components in the high‐density optical communication system, and R&D interest is focused intensively on this component. This paper presents a vector mode analysis of a fiber with arbitrary refractive index distribution and without axial symmetry, such as an elliptic fiber with arbitrary refractive index distribution, which has been mentioned as one possible optical fiber. An approximate vector solution is proposed. The approximate vector analysis is a practical method of analysis, in that the numerical computation required is that employed in the approximate scalar solution itself, which is simple and obvious, since most of the computation is analytic, and it is possible to determine directly the difference of propagation constants of the two vector modes in the single‐mode optical fiber. The paper discusses the theory, accuracy and application of the approximate vector analysis.