Transmission properties of a low−loss near−parabolic−index fiber

Pulse dispersion, refractive−index profile, and loss measurements were made on a low−loss graded−index optical fiber fabricated by a chemical vapor deposition technique. The transmission loss spectra had a minimum value of 3.8 dB/km at 1.06−μm wavelength. The core refractive index had a power−law profile with an exponential coefficient of 2.2±0.1. Mode−mixing effects and the near−parabolic−index profile in a 5.6−km extrapolated fiber length (actual length =1.12 km) reduces modal dispersion by a factor of 17 from the result expected for an ungraded step−index fiber.