The propagation properties analysis of asymmetric fiber couplers

The finite element method mode analysis of optical waveguides in asymmetric fiber couplers is presented. An adaptive-size triangular mesh is employed to obtain the propagation constants of the first four modes in different constructions. The numerical result shows that the radius ratio has obvious effects on the propagation constant of even and odd modes at the same degree of fiber fusion. Compared with the odd mode, the propagation constant of the even mode is insensitive to the changes of the degree of fiber fusion.