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.

I. Introduction

THE NONLINEAR refractive index of an optical fiber is a key parameter for designing future ultrahigh capacity transmission systems since their transmission characteristics would be degraded by various nonlinear effects [1]. It is important, therefore, to evaluate the nonlinear refractive index of a single-mode fiber accurately.