Four Wave Mixing Suppression

Abstract

Methods, systems and computer program products for countering the effects of four wave mixing are described. In one implementation, a controller can be used to shift an operating wavelength of an optical transmitter away from a zero-dispersion wavelength through which signals of the optical transmitter are transmitted. The controller can perform the shifting process while allowing sufficient margin for division multiplexing and minimal dispersion. The controller may determine an appropriate offset to be used for shifting the operating wavelength without subjecting the signals to a significant increase in undesirable effects such as dispersion, crosstalk and signal distortion which can impact the overall bit-error rate.

1 . A method comprising:
 receiving information associated with a first wavelength;   receiving information associated with a second wavelength;   determining an offset based on the first wavelength and the second wavelength; and   controlling an output parameter associated with an optical transmitter based on the offset.   
     
     
         2 . The method of  claim 1 , where receiving information associated with the first wavelength includes receiving a user input specifying an operating wavelength associated with the optical transmitter. 
     
     
         3 . The method of  claim 2 , where receiving information associated with the second wavelength includes retrieving the second wavelength from a database storing information associated with one or more zero dispersion wavelengths each corresponding to a particular optical fiber. 
     
     
         4 . The method of  claim 1 , where receiving information associated with the second wavelength includes receiving a user input specifying a zero dispersion wavelength associated with an optical fiber through which the output of the optical transmitter is to be transmitted. 
     
     
         5 . The method of  claim 1 , where determining the offset includes comparing the first wavelength to the second wavelength to determine whether the first wavelength matches the second wavelength. 
     
     
         6 . The method of  claim 5 , where determining the offset is performed when the first wavelength matches the second wavelength. 
     
     
         7 . The method of  claim 1 , further comprising prompting a user to indicate whether the determined offset is acceptable. 
     
     
         8 . The method of  claim 7 , where prompting the user is performed after controlling the output parameter based on the determined offset. 
     
     
         9 . The method of  claim 7 , further comprising:
 receiving a confirmation from the user that the determined offset is acceptable; and   setting an output wavelength as the output parameter based on the determined offset and the received confirmation.   
     
     
         10 . The method of  claim 7 , further comprising:
 receiving a confirmation from the user that the determined offset is unacceptable;   determining a second offset different from the determined offset;   prompting the user to indicate whether the second offset is acceptable; and
 adjusting the output parameter including adjusting an output wavelength associated with the optical transmitter based on the second offset upon receiving a confirmation from the user that the second offset is acceptable. 
   
     
     
         11 . The method of  claim 1 , where receiving information associated with the first wavelength and receiving information associated with the second wavelength include receiving both wavelengths from a same source. 
     
     
         12 . The method of  claim 1 , where controlling the output parameter includes shifting the first wavelength away from the second wavelength to minimize signal distortion associated with four wave mixing. 
     
     
         13 . The method of  claim 12 , where:
 receiving the information associated with second wavelength includes retrieving, from a database, a zero dispersion wavelength associated with a transmission medium through which outputs of the optical transmitter are to be transmitted;   receiving the information associated with first wavelength includes receiving a user input identifying an operating wavelength associated with the optical transmitter; and   controlling the output parameter includes shifting the operating wavelength away from the zero dispersion wavelength based on the determined offset.   
     
     
         14 . The method of  claim 1 , further comprising:
 developing a database containing a plurality of offsets;   identifying an offset from the plurality of offsets as the determined offset based on one or more criteria; and   receiving user confirmation indicating that the offset is satisfactory,   where controlling the output parameter includes controlling the output parameter using the offset.   
     
     
         15 . The method of  claim 14 , where identifying the offset includes:
 measuring the plurality of offsets against one or more design parameters; and   identifying an offset with a best measurement result as the offset.   
     
     
         16 . The method of  claim 1 , further comprising receiving user input overriding the determined offset,
 where controlling the output parameter includes controlling the output parameter based on the user input.   
     
     
         17 . The method of  claim 1 , further comprising receiving user information indicating that the determined offset is acceptable,
 wherein controlling the output parameter is performed after receiving the user information.   
     
     
         18 . A system comprising:
 an optical transmitter that transmits an optical signal through a transmission medium; and   a controller that:
 receives information associated with a first wavelength; 
 receives information associated with a second wavelength; 
 determines an offset based on the first wavelength and the second wavelength; and 
 controls an output parameter associated with the optical transmitter based on the offset. 
   
     
     
         19 . The system of  claim 18 , further comprising a database of second wavelengths including one or more zero dispersion wavelengths associated with one or more corresponding transmission mediums and corresponding offsets. 
     
     
         20 . The system of  claim 19 , wherein the controller identifies a zero dispersion wavelength corresponding to the transmission medium in the database, and the determined offset based on the zero dispersion wavelength. 
     
     
         21 . The system of  claim 19 , wherein the second wavelengths includes at least one wavelength at 1550 nm or 1310 nm corresponding to a zero dispersion wavelength of an optical fiber.