DESIGN OF STRAIN-FREE-FIBER WITH NONUNIFORM DOPANT CONCENTRATION FOR STIMULATED BRILLOUIN-SCATTERING SUPPRESSION

The loss and dispersion properties of fibers with a nonuniform dopant concentration along their length are investigated theoretically and si mple equations are obtained for loss and dispersion estimation. These equations are used to discuss fiber properties and a design procedure by which to achieve SBS suppression. The loss increases by 0.02-0.03 d B/km/% and the dispersion decreases by -2.4 ps/km/nm/% as the relative -index change due to dopant increases longitudinally. It is found that a large change in the dopant concentration along a fiber is effective in suppressing SBS.