Iterative carrier-phase estimation and data recovery for coherent optical receivers

A receiver for an optical signal modulated by symbols over a sequence of symbol periods, comprising:

• a detector adapted to mix the modulated optical signal with a local-oscillator (LO) signal to produce a digital measure of the modulated optical signal for the sequence;
• and
• a digital processor being coupled to receive the digital measure and being adapted to process the digital measure to recover data carried by the modulated optical signal, wherein, for each one of the symbol periods from the sequence, the digital processor is adapted to:
• derive a digital signal corresponding to the one of the symbol periods from the digital measure;
• generate a first estimate of a carrier-phase offset between the LO signal and a carrier of the modulated optical signal based on the digital signal;
• generate a first estimate of the symbol carried by the modulated optical signal in said one of the symbol periods based on the first estimate of the carrier-phase offset;
• generate a second estimate of the carrier-phase offset based on the first estimate of the symbol;
• and
• generate a second estimate of the symbol carried by the modulated optical signal in said one of the symbol periods based on the second estimate of the carrier-phase offset.