Abstract: A device for measuring dispersion of a link between two switching nodes of an optical network comprises a phase measuring unit PMU for determining a first phase of a data signal traveling on a first wavelength &lgr;1, and a second phase of the same data signal traveling on a second wavelength &lgr;2, received consecutively over the link under measurement. A dispersion measurement controller controls operation of the phase measuring unit and characterizes the dispersion of the link at a wavelength of interest &lgr;=(&lgr;1+&lgr;2)/2, based on the first and second phases. The PMU includes a frame detector for determining a first and a second rotation signal indicative of the digital offset between the first and second test clocks with a respective frame start, and a phase detector for measuring the phase of these test clocks with respect to a static reference. The static reference is provided by the same data signal transmitted continuously over a reference wavelength.

Abstract: A device for measuring dispersion of a link between two switching nodes of an optical network comprises a phase measuring unit PMU for determining a first phase of a data signal traveling on a first wavelength &lgr;1, and a second phase of the same data signal traveling on a second wavelength &lgr;2, received consecutively over the link under measurement. A dispersion measurement controller controls operation of the phase measuring unit and characterizes the dispersion of the link at a wavelength of interest &lgr;=(&lgr;1+&lgr;2)/2, based on the first and second phases. The PMU includes a frame detector for determining a first and a second rotation signal indicative of the digital offset between the first and second test clocks with a respective frame start, and a phase detector for measuring the phase of these test clocks with respect to a static reference. The static reference is provided by the same data signal transmitted continuously over a reference wavelength.

Abstract: Dispersion is measured for an end-to-end link using two carrier wavelengths with a phase-synchronized signal modulated on each, and a single receiver that detects the BER of the combined fields. The power ratio of the two fields is chosen such that the weaker field modulates the eye of the stronger field, leading to slight periodic eye closure BER(&tgr;)≅BER(&tgr;+TB) whenever the relative group delay changes by the bit period TB. The magnitude of the relative group delay can therefore be inferred from the undulated BER response as a function of the wavelength detuning. A fit function is selected for the group delay response and the dispersion parameter D and dispersion slope S are calculated from this fit function after the function parameters are determined.