Abstract: The electromagnetic field characteristics of opticalwaveguides in asymmetry fiber couplers are investigated by a finite element method. An adaptive-size triangular mesh is employed to obtain the propagation constants of the first four modes in different constructions. Numerical result shows that the propagation constants of even and odd modes are obviously affected by the radius ratio of the two fibers composing the coupler. In comparison with odd mode, the propagation constant of even mode is insensitive to fusion degree of fibers.

Key words: optical fiber communications, finite element method, asymmetry fiber couplers, propagation constant