Method and system for automatic feedback control for fine tuning a delay interferometer

Abstract

A method for receiving an optical signal is included where an ingress signal is split into a first portion and a second portion. A relative delay is induced between the first portion and the second portion, which are optically interfered to generate at least one interfered signal. Quality criteria of a monitored signal at least based on the at least one interfered signal is monitored so that a relative delay based in the quality criteria may be adjusted.

1 . A method for receiving an optical signal, comprising: splitting an ingress signal into a first portion and second portion; inducing a relative delay between the first portion and the second portion; optically interfering the first and second portions to generate at least one interfered signal; monitoring a Bit Error Rate (BER) estimate of a monitored signal at least based on the at least one interfered signal; and adjusting the relative delay based on the BER estimate. 
   
   
       2 . The method of  claim 1 , wherein the BER estimate is obtained from a number of errors corrected per frame detected by a Forward Error Correction (FEC) unit. 
   
   
       3 - 24 . (canceled) 
   
   
       25 . A method for transmitting and receiving an optical signal, comprising:
 transmitting the optical signal using a transmitter;   receiving the optical signal using a receiver, the receiver including an interferometer, the interferometer: splitting the optical signal into a first portion and second portion; inducing a phase shift between the first portion and the second portion; and optically interfering the first and second portions to generate at least one interfered signal;   monitoring a Bit Error Rate (BER) estimate of a monitored signal at least based on the at least one interfered signal; and   adjusting the phase shift based on the BER estimate.   
   
   
       26 . The method as recited in  claim 25  wherein the transmitter and receiver are part of a WDM system. 
   
   
       27 . The method as recited in  claim 25  wherein the phase shift is adjusted by adjusting a relative delay in the interferometer. 
   
   
       28 . The method as recited in  claim 25  wherein the receiver includes a device for adjusting the phase shift between the first and second portions. 
   
   
       29 . A method for transmitting and receiving an optical signal, comprising:
 transmitting the optical signal using a transmitter;   receiving the optical signal using a receiver, the receiver including an interferometer, the interferometer: splitting the optical signal into a first portion and second portion; inducing a phase shift between the first portion and the second portion; and optically interfering the first and second portions to generate at least one interfered signal;   monitoring a Bit Error Rate (BER) estimate of a monitored signal at least based on the at least one interfered signal; and   canceling phase shifts in the interferometer by adjusting a phase shift between the first portion and the second portion.   
   
   
       30 . The method as recited in  claim 29  wherein the receiver includes a device for adjusting the phase shift between the first and second portions. 
   
   
       31 . The method as recited in  claim 29  further comprising feeding back the BER estimate. 
   
   
       32 . The method as recited in  claim 29  wherein the canceled phase shifts are caused by the transmitter.