Abstract

The transmission performance of ultralong-distance optical communication systems critically depends on fiber chromatic dispersion.¹ To achieve desired performance, system designers require knowledge of the zero-dispersion wavelength, λ₀, to within 0.1 nm.¹ We have developed two laser-based systems to measure λ₀, of long optical fibers. Both systems are based on tunable narrow-line laser sources with output wavelengths that can be accurately measured with an interferometric wavemeter. The first system uses the phase-shift method to measure group delay in the fiber sample as a function of wavelength² The second system directly measures the wavelength-averaged differential group delay or fiber chromatic dispersion by dithering the laser wavelength in a new implementation of the differential phase-shift technique³. Both systems give λ₀ with a precision (repeatability) of 0.02 nm or less at the 99% confidence level.

© 1996 Optical Society of America