Measurement of the nonlinear refractive index in optical fiber by the cross-phase-modulation method with depolarized pump light.

Depolarized pump light is used in measurements of the nonlinear refractive index, n2, in optical fiber by the cross-phase-modulation method. High measurement repeatability within ±1% is obtained by this method. The nonlinear refractive index is determined for dispersion-shifted fiber, standard single-mode fiber, pure silica-core single-mode fiber, and dispersion-compensating fiber as 3.35 × 10−20, 2.96 × 10−20, 2.79 × 10−20, and 4.44 × 10−20 m2/W, respectively, at 1.55 μm. This shows that the nonlinear refractive indices of the optical fibers differ greatly according to glass composition.