Abstract

Methods are developed for extracting from a numerical propagating-beam solution of a scalar wave equation the information necessary to compute the impulse-response function and the pulse dispersion for a multimode graded-index fiber. It is shown that the scalar Helmholtz equation and the parabolic wave equation have the same set of eigenfunctions in common and that the eigenvalues for the two equations are simply related. Thus one can work exclusively with the simpler parabolic equation. Both the mode eigenvalues (propagation constants) and mode weights, which are necessary for determining the impulse response, can be obtained with high accuracy from a numerical Fourier transform of the complex field-correlation function by the use of digital-filtering techniques. It is shown how a solution obtained in the absence of profile dispersion can be simply corrected for the presence of profile dispersion. In an illustrative example a graded-index fiber with a central dip in its profile is considered.

© 1979 Optical Society of America

Computation of mode eigenfunctions in graded-index optical fibers by the propagating beam method

M. D. Feit and J. A. Fleck
Appl. Opt. 19(13) 2240-2246 (1980)

Mode properties and dispersion for two optical fiber-index profiles by the propagating beam method

M. D. Feit and J. A. Fleck
Appl. Opt. 19(18) 3140-3150 (1980)

Computation of mode properties in optical fiber waveguides by a propagating beam method

M. D. Feit and J. A. Fleck
Appl. Opt. 19(7) 1154-1164 (1980)

Light propagation in graded-index optical fibers

M. D. Feit and J. A. Fleck
Appl. Opt. 17(24) 3990-3998 (1978)

Propagation constants and group delays of guided modes in graded-index fibers: a comparison of three theories

Gunnar Jacobsen and J. J. Ramskov Hansen
Appl. Opt. 18(16) 2837-2842 (1979)