Measurement of the nonlinear index of silica-core and dispersion-shifted fibers.

We have accurately measured the nonlinear refractive index, n2, of the glass found in silica-core and dispersion-shifted optical fibers. We find that at 1.319 µm the n2 of silica-core and dispersion-shifted fibers is 2.36 × 10−16 and 2.52 × 10−16 cm2/W (±5%), respectively. We also estimate that the n2 of germania is three times the n2 of pure silica. Because the wavelength dependence of n2 between 1.3 and 1.5 µm is known to be small, our measured values should also be valid at 1.55 µm.