Precise laser-based measurements of zero-dispersion wavelength in single-mode fibers

We have developed two laser-based systems to measure the zero-dispersion wavelength (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 wavelength. 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 technique. Both systems give λ₀ with a precision (repeatability) of 0.02 nm or less at the 99% confidence level.