Effet de phase dans la dispersion de la puissance lumineuse des fibres optiques unimodales

Pulse broadening calculations in monomode fibers do not include till now the phase variation of the coherent input field. Although it is correct to ignore this variation at wavelengths different from the zero material dispersion wavelength lambda(o), this effect must be taken into account for wavelengths nearly equal to lambda(o). We have found for silica-type fibers that if the relative source linewidth (Deltalambda(o))/lambdao is less than 10(-3), the phase effect largely dominates over important distances in the evaluation of the pulse broadening giving rise to a decrease of the r.m.s. output pulse width. Therefore, this effect must be relevant for the estimation of the maximum information capacity on monomode fibers.