Optical supervisory channel apparatus and method for measuring optical properties
AssigneeCiena Corporation
InventorsVipul Bhatnagar, Balakrishnan Sridhar, Michael Y. Frankel, Prasad Dasika
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Abstract
A service channel modem is adapted to determine optical properties of an optical fiber link connecting two nodes. The optical service channel (OSC) communicates an optical reference parameter over the fiber link. An optical parameter of the OSC transmitted over the fiber link is measured. By recovering the optical reference parameter from the OSC and using the measured optical parameter, certain optical properties may be determined including link loss, multi-path interference, and chromatic dispersion. When measuring chromatic dispersion, one of the fiber links serves as a synchronization reference and the other is the link being measured.
Claims21
An apparatus for using an optical service channel to determine an optical property of an optical link connecting a first node and second node of an optical communications system, comprising:
- a laser optically coupled to the optical link, said laser being modulated by a signal to generate the optical service channel being launched into the optical link, wherein the signal includes a reference optical parameter;
- an optical service channel detector optically coupled to the optical link, said optical service channel detector detecting the optical service channel and recovering the reference optical parameter from the detected optical service channel;
- said optical service channel detector also measuring an optical parameter of the optical service channel to generate a measured optical parameter;
- and
- a controller operatively connected to said optical service channel detector, said controller calculating an optical property of the optical link based on the recovered reference optical parameter and the measured optical parameter.
A system for measuring chromatic dispersion, comprising:
- a west service channel modem including an oscillator generating an RF tone;
- a west laser operatively connected to said RF oscillator, said west laser being modulated by a west signal to generate an eastbound optical service channel being launched into the west-east optical link, wherein the west signal modulating said west laser includes the RF tone generated by said oscillator;
- an east service channel modem including
- an east detector converting the eastbound optical supervisory channel to an electrical signal and recovering the RF tone to produce a recovered RF tone;
- and
- a tunable east laser operatively connected to said east detector, said tunable east laser being modulated by an east signal to generate a westbound optical supervisory channel being launched into a east-west optical link;
- said tunable east laser tuning a center wavelength of the westbound optical service channel to at least two different wavelengths,
- said west SCM further including
- a west detector converting the westbound optical supervisory channel to an electrical signal and recovering the recovered RF tone to produce a re-recovered RF tone;
- a phase detector operatively connected to said west detector and to said RF oscillator, said phase detector detecting a phase difference between the RF tone from said RF oscillator and the re-recovered RF tone from said west detector;
- and
- a dispersion calculator operatively connected to said west detector, said dispersion calculator calculating a chromatic dispersion value for the east-west optical link based on the phase difference detected by said phase detector and wavelength data representing the at least two different wavelengths.
A method of determining an optical property of an optical link in a wavelength division multiplexed (WDM) optical system having a plurality of nodes and an optical supervisory channel between adjacent nodes including a first node and a second node interconnected by the optical link capable of carrying a WDM signal and the optical supervisory channel, the method comprising:
- utilizing the optical supervisory channel to communicate a first optical reference parameter between the first and second nodes;
- measuring an optical parameter of the optical supervisory channel received by the second node to generate a measured optical parameter;
- and
- calculating an optical property of the optical link interconnecting the first and second nodes based on the first optical reference parameter and on the measured optical parameter.
Dependencies are inferred from the claim text.