1. A method of recovering a most likely value of each symbol transmitted through an optical communications network using a high speed optical signal, the method comprising, in a receiver of the network, steps of: a data path of the receiver processing a stream of multi-bit digital samples of the optical signal using a first compensation function to generate a respective soft decision value {tilde over (X)}(n) of each transmitted symbol; and a non-linear compensator applying a second compensation function to each soft decision value {tilde over (X)}(n) to generate a most likely symbol value {circumflex over ({circumflex over (X)}(n); wherein processing the stream of multi-bit digital samples of the optical signal comprises: processing the multi-bit digital samples to generate multi-bit symbol estimates X′(n) of transmitted symbols; and rotating a respective phase of each symbol estimate X′(n) to compensate a frequency mismatch between a local oscillator and a carrier of the optical signal.