Dopant dependence of effective nonlinear refractive index in GeO₂- and F-doped core single-mode fibers

We describe the dopant dependence of the effective nonlinear refractive index n/sub 2eff/ in GeO/sub 2/- or F-doped core fibers theoretically and experimentally. We show that the dopant dependence of the nonlinear refractive index n/sub 2/ of F-doped bulk glass is the inverse of that of GeO/sub 2/-doped bulk glass. We also show that the effective nonlinear refractive index n/sub 2eff/ in F-doped core fibers, estimated by using the dopant content dependence of n/sub 2/, is in good agreement with our experimental results. Moreover, we confirm that n/sub 2eff/ in an optical fiber strongly depends on the refractive index profile of its core.