Analysis of optical fibers by the effective-index method.

The effective-index method for determining waveguide dispersion is derived from the scalar wave equation and applied to optical fibers of arbitrary cross-sectional shapes. In the simplest use of the method, the optical fiber is replaced by an equivalent slab waveguide with an index profile derived from the geometrical shape of the fiber. Results from analyzing circular, elliptical, and cusp-shaped fibers are used to illustrate the general features of the method. A procedure is also given for improving the accuracy of the method applied to a class of single-mode fiber.