Comments on "on the analysis of a weakly guiding doubly clad dielectric optical fiber with an annular core"

A discussion of the dispersion relation of the modes guided by an annular core fiber is done in order to prove that the fundamental mode has a zero cutoff. It also gives the inequalities satisfied by the cutoff frequencies of the first lower modes. A relation is established between the propagation constants of two modes with the same radial order but different azimuthal orders. It allows its to precisely set the conditions for these constants to be almost similar. Numerical results are shown to confirm these assertions. (C) 2003 Wiley Periodicals, Inc.