Numerical and simulation analyses on supermode characteristics of dual-core fiber and four-core fiber

In this paper, supermode characteristics of a dual-core fiber and a four-core fiber are analyzed by a simple couple-mode theory. The effective refractive index and corresponding relative error of each supermode are investigated in detail with different gapsize, relative refractive index and core radius using numerical method and finite element method. Both adjacent coupling and non-adjacent coupling are taken into consideration when keeping single mode condition of each core. The magnitude of relative error can achieve 10−5 and 10−4 for a dual-core structure and a four-core structure, respectively. The obtained results clearly show the validation of numerical method compared with finite element method. One is going to benefit from the succinct equation expressions in this paper when designing and analyzing supermode supporting fiber structure.