AN EFFICIENT NUMERICAL APPROACH FOR DETERMINING THE DISPERSION CHARACTERISTICS OF DUAL-MODE ELLIPTIC-CORE OPTICAL FIBERS

Based on vectorial formulations which combine the surface integral equ ation method and the finite-element method, a novel numerical approach is proposed for calculating the dispersion coefficients of dual-mode elliptical-core fibers with arbitrary refractive index profiles, By di fferentiating the original formulations involving the propagation cons tant beta and the guided mode fields H-x and H-y once and twice with r espect to the normalized frequency V, the new formulations for {d beta /dV,dH(x)/dV,dH(y)/dV} and for {d(2) beta/dV(2),d(2)H(x)/dV(2),d(2)H(y )/dV(2)} are obtained, respectively. Once {beta,H-x,H-y} is solved thr ough the eigenvalue procedure which dominates the computing time, only a few matrix manipulations are required to obtain {d beta/dV,dH(x)/dV ,dH(y)/dV} and {d(2) beta/dV(2),d(2)H(x)/dV(2),d(2)H(y)/dV(2)}. Some n umerical examples are examined to see the influence of different refra ctive index distributions with dips on the dispersions of the four non degenerate LP(11) modes for elliptical-core fibers.