Single‐mode propagation in multi‐layer elliptical fiber waveguides

Single mode propagation in three‐layer step index elliptical fiber waveguides is investigated theoretically. Previous analysis of the elliptical dielectric tube waveguide is extended to include cladded, W‐type and tube‐type fibers. Numerical results on cutoff characteristics of the first higher‐order mode and phase coefficient, group velocity and power distribution characteristics of the dominant modes are presented over a wide range of parameters. A two‐layer step index elliptical fiber waveguide is presented as a special case. High eccentricity single mode fibers have small modal beat lengths but have small core size and greater power distribution in the claddings. W‐type fiber in the middle range of eccentricities is suggested for single mode single polarization applications.