Minimization of the chromatic dispersion over a broad wavelength range in a single-mode optical fiber

The effective refractive index as a function of vacuum wavelength is approximated by Lagrange interpolation polynomials. The rms value of the chromatic dispersion is then calculated analytically. It is demonstrated that use of fourth-degree polynomials is far more efficient than the use of second-degree polynomials. The rms value of the chromatic dispersion over the wavelength range (1.25 mum, 1.60 mum) is calculated and minimized for step-index fibers, triangular index fibers, and alpha-power fibers. The full vector solution of Maxwell's equations is used. The error induced by the approximate refractive-index model is found to be negligible at the point of minimum dispersion.