Receiver Laser Phase Noise Estimation With Application to EEPN Control

In data communication using pulse transmission with excess bandwidth, sidebands of the received spectrum contain redundant information. In fiber-optic communications, signal components in these sidebands experience temporal walk-off caused by fiber dispersion. Extracting the sidebands via suitable signal processing and exploiting the redundancy enables estimation of the derivative of the receiver-laser phase noise. This allows receiver-laser phase noise to be compensated for separately from transmitter-laser phase noise, thereby avoiding equalizer-enhanced phase noise (EEPN). Extensive computer simulations comparing this technique with existing EEPN control methods demonstrate that the technique operates over a wider range of signal-to-noise ratios, and can provide improved bit error rates and system reach.