Method and system for distributed measurement and compensation of chromatic dispersion in an optical network

A network comprising:

• a plurality of wavelength-channel switching nodes;
• a plurality of transport modules;
• a plurality of fiber-optic links interconnecting said switching nodes, each link comprising at least one span, each span terminating in one of said transport modules;
• a plurality of probing-signal generators associated with selected switching nodes;
• a plurality of probing-signal detectors, each detector collocated with a respective transport module;
• a first controller for directing a first probing signal, produced by a first probing-signal generator associated with a first switching node from among said selected switching nodes, to a first route traversing at least one detector;
• and
• a processing unit for processing outputs of said at least one detector.

A method for distributed measurement of chromatic-dispersion in a network comprising a plurality of optical switching nodes, the method comprising:

• sending from a first switching node, from among said plurality of optical switching nodes, a probing optical signal combined with operational optical signals, said probing optical signal comprising segments each having a selected wavelength, from a set of wavelengths, during successive time intervals, said optical signal modulated by a probing tone of a periodic waveform and a predetermined frequency;
• detecting, at a probing-signal detector placed along a path from said first switching node, said probing tone and determining phase differences between successive parts of said probing tone corresponding to said segments;
• and
• determining, at a processing unit coupled to said first optical switching node and to said probing-signal detector, chromatic dispersion along said path between said first switching node and said probing-signal detector for pairs of said wavelengths according to:
• said phase differences;
• and
• said predetermined frequency.