Phase shift technique for the measurement of chromatic dispersion in optical fibers using LED's

A sinusoidal technique is reported, which allows simple and accurate measurements of chromatic dispersion in optical fibers. It is based on the phase shift which a sinusoidally modulated fight beam undergoes while traveling along a fiber when its wavelength is changed. The choice of a multiple LED's source permits the continuous spectral covering from 750 to 1600 nm;easily available instrumentation and devices are needed for the measurement setup. The technique is reported in detail by showing results obtained in multimode fibers; statistical evaluation of its accuracy and a comparison with conventional methods are carried out. An accuracy of a few picoseconds in relative delay and of ∓1 ps/nm . km in chromatic dispersion are demonstrated, that compare very favorably with the existing techniques.