INTERESTING EFFECT OF OPTICAL KERR NONLINEARITY IN EXPANDING SINGLE-MODE REGIME OF OPTICAL FIBERS USING DISPERSION-FLATTENED PROFILES

An interesting effect of optical Kerr nonlinearity is reported from th eoretical investigation on the fundamental and first higher mode cutof f frequencies in single-mode fibers doped with highly nonlinear materi als like CdSxSe1-x with W-type dispersion-flattened profiles. It is ob served that whereas the single-mode regime decreases absolutely for di spersion-shifted profiles due to reduction of the first higher order m ode cutoff frequency as is evident from earlier studies, it increases for W-type profiles for such nonlinearity taking its effect on the non zero fundamental mode cutoff frequency into consideration. Thus, one c an go further down below the fundamental mode cutoff frequency while u sing W-fibers in single mode nonlinear fiber devices involving evanesc ent field coupling in the low V region. (C) 1998 Elsevier Science B.V. All rights reserved.