Feedback controlled raman amplification in optical system

Abstract

An optical communication link that includes two nodes interconnected by an optical channel that comprises optical fiber(s), and that is used to communicate an optical signal comprising multiple optical signal wavelengths. The first node provides an optical signal onto the optical channel towards the second node, or receives an optical signal from the optical channel from the second node. A Raman pump provides Raman pump power into the optical fiber of the optical channel to thereby perform Raman amplification of the optical signal in the optical fiber. The second node determines a quality measurement of at least of optical wavelength signals transmitted by the first node to the second node. The second node also transmits information from the quality measurement back to the first node. A controller at the first node controls at least one parameter of the Raman pump in response to this transmitted information.

What is claimed is: 
     
         1 . An optical communication link comprising:
 a first node comprising an optical channel interface for providing an optical signal onto an optical channel comprising an optical fiber towards a second node, or for receiving the optical signal from the optical channel from the second node, the optical signal comprising a plurality of optical wavelength signals;   a Raman pump for providing Raman pump power into the optical fiber to thereby perform Raman amplification of the optical signal in the optical fiber;   a second node of an optical communication link comprising a signal quality determination mechanism for determining a quality measurement of at least one of the plurality of optical wavelength signals transmitted by the first node to the second node;   a communication interface to transmit information from the quality measurement from the second node to the first node; and   a controller within the first node for controlling at least one parameter of the Raman pump in response to the transmitted information from the quality measurement.   
     
     
         2 . The optical communication link in accordance with  claim 1 ,
 wherein the optical channel interface provides the optical signal onto the optical channel rather than receives the optical signal from the optical channel; and   wherein the Raman pump is a forward Raman pump.   
     
     
         3 . The optical communication link in accordance with  claim 2 , the controller following an improvement method in response to the quality parameter. 
     
     
         4 . The optical communication link in accordance with  claim 1 , the quality parameter being a bit error rate measurement. 
     
     
         5 . The optical communication link in accordance with  claim 1 , the communication interface configured to use optical signal overhead of at least one of a plurality of optical wavelength signals transmitted by the second node to the first node in order to transmit the information from the quality measurement to the first node. 
     
     
         6 . The optical communication link in accordance with  claim 1 ,
 the signal quality determination mechanism for determining a quality measurement of at least some of the plurality of optical wavelength signals transmitted by the first node to the second node;   the communication interface transmitting information from the quality measurements from the second node to the first node; and   the controller within the first node controlling at least one parameter of the Raman pump in response to the transmitted information from the quality measurements.   
     
     
         7 . The optical communication link in accordance with  claim 1 ,
 the signal quality determination mechanism for determining a quality measurement of all of the plurality of optical wavelength signals transmitted by the first node to the second node;   the communication interface transmitting information from the quality measurements from the second node to the first node; and   the controller within the first node controlling at least one parameter of the Raman pump in response to the transmitted information from the quality measurements.   
     
     
         8 . The optical communication link in accordance with  claim 1 ,
 wherein the optical channel interface receives the optical signal from the optical channel rather than provides the optical signal onto the optical channel; and   wherein the Raman pump is a backward Raman pump.   
     
     
         9 . A first node of an optical communication link, the first node comprising:
 an optical channel interface for providing an optical signal onto an optical channel to a second node, or for receiving an optical signal from the optical channel from a second node, the optical channel comprising an optical fiber, the optical signal comprising a plurality of optical wavelength signals, the optical channel interface further for receiving from the second node a quality measurement taken at the second node of at least one of the plurality of optical wavelength signals transmitted by the first node to the second node;   a Raman pump for providing Raman pump power into the optical fiber to thereby perform Raman amplification of the optical signal in the optical fiber; and   a controller for controlling at least one parameter of the Raman pump in response to the received quality measurement.   
     
     
         10 . The first node in accordance with  claim 9 ,
 the optical channel interface comprising a first channel interface portion for providing the optical signals onto the optical channel rather than for receiving the optical channels from the optical channel, and a second channel interface portion for receiving the quality measurement from the second node,   wherein the Raman pump is a forward Raman pump.   
     
     
         11 . The first node in accordance with  claim 10 , the optical channel being a first optical channel, the optical signal being a first optical signal, the plurality of optical wavelength signals being a first plurality of optical wavelength channels,
 the second channel interface portion further for receiving a second optical signal from a second optical channel from a second node, the second optical signal comprising a second plurality of optical wavelength channels.   
     
     
         12 . The first node in accordance with  claim 11 , the second channel interface portion configured to receive the quality measurement from an optical signal overhead of at least one of the plurality of optical wavelength signals transmitted by the second node to the first node. 
     
     
         13 . The first node in accordance with  claim 9 , the quality measurement being or being derived from a bit error rate of at least one of the plurality of optical wavelength signals. 
     
     
         14 . A method for a first node in an optical communication link performing distributed Raman amplification of an optical signal on an optical fiber, the method comprising:
 an act of an optical channel interface interfacing with an optical signal on an optical channel that comprises an optical fiber and that leads to a second node in the optical communication link, the optical signal comprising a plurality of optical wavelength signals;   an act of a Raman pump providing Raman pump power into the optical fiber to thereby perform Raman amplification of the optical signal in the optical fiber;   an act of receiving a signal quality measurement from the second node; and   an act of controlling at least one parameter of the Raman pump in response to the signal quality measurement.   
     
     
         15 . The method in accordance with  claim 14 , the act of receiving and controller performed repeated to improve the signal quality measurement over time. 
     
     
         16 . The method in accordance with  claim 14 , the act of the optical channel interface interfacing with the optical signal comprising:
 an act of the optical channel interface transmitting the optical signal onto the optical channel towards the second node, the Raman pump being a forward Raman pump.   
     
     
         17 . The method in accordance with  claim 14 , the optical channel interface being a first optical channel interface, the optical signal being a first optical signal, the plurality of optical wavelength signals being a first plurality of optical wavelength signals, the method further comprising:
 an act of a second optical channel interface receiving a second optical signal over a second optical channel from the second node, the second optical signal comprising a second plurality of optical wavelength signals.   
     
     
         18 . The method in accordance with  claim 17 , the second optical channel interface also used to perform the act of receiving the signal quality measurement from the second node. 
     
     
         19 . The method in accordance with  claim 18 , the signal quality measurement being in an optical signal overhead of at least one of second plurality of optical wavelength signals transmitted by the second node to the first node. 
     
     
         20 . The method in accordance with  claim 14 , the act of the optical channel interface interfacing with the optical signal comprising:
 an act of the optical channel interface receiving the optical signal from the optical channel, the Raman pump being a backward Raman pump.