In this paper, the effective refractive index of the M-type triple clad single-mode elliptical optical fiber was investigated. These kinds of multilayer optical fibers are useful for zero dispersion wavelength shifted applications. The effects of the optical and geometrical parameters on the effective refractive index were examined. The finite element method (FEM) was used for modal analysis. The simulation results indicated that by increasing the elliptical factor the effective refractive index was reduced and made the electrical field distribution to be smoother in the core and cladding layers. Also, by the growth of the core radius and ∆, the effective refractive index was raised. Furthermore with increase of the P, Q, R1 and R2 amplitude, the effective refractive index reduces. The concept to consider is that the effective refractive index sensitivity to wavelength was reduced by higher values of P.
