Patent ID: 9025969
Filing Date: 2015-05-05
Classification: H04B

Abstract:
1. A method of signal processing in an optical communications receiver, the method comprising: receiving a modulated optical signal; coherently detecting the modulated optical signal and generating a first in-phase (I) component signal and a first quadrature (Q) component signal; converting the first I component signal and the first Q component signal into a first digital I signal and a first digital Q signal; adaptively equalizing the first digital I signal and the first digital Q signal to compensate for channel distortion introduced into the received modulated optical signal from a communication channel; decoding, by a digital interferometer, the equalized first digital I signal and the first digital Q signal to generate an output signal; and receiving the output signal, mapping the output signal to a phase angle signal using a look-up table, and using the phase angle signal to compensate for phase distortion in the received output signal caused by a local oscillator frequency offset (LOFO) and generate a compensated output signal from which data information is recovered, the phase distortion introduced into the first I component signal and the first Q component signal by a local oscillator signal utilized during coherent detection of the modulated optical signal.