Joint acquisition of chromatic dispersion and frequency offset in optical systems

A method implemented in an optical transceiver, the method comprising:

• receiving, by a receiver module, a data payload;
• determining, by a processor, a training preamble based on an amount of time available for an optical receiver associated with the optical transceiver to establish timing alignment and to process the training preamble, wherein the training preamble comprises only a plurality of a same data sequence, and wherein the data sequence comprises a basic data sequence to reduce cross-correlation and maintain orthogonality between X-polarization components and Y-polarization components;
• and
• transmitting, by a transmitter module, the training preamble and the data payload to an optical receiver to provide for acquisition of a timing synchronization between the optical receiver and the training preamble.

A method for compensating for impairments in an optical signal and implemented in an optical transceiver in a communications network, the method comprising:

• receiving, from an optical transmitter, an optical signal;
• determining, according to the optical signal, a chromatic dispersion (CD) estimate and a local oscillator frequency offset (LOFO) estimate for joint compensation jointly according to a relationship between a plurality of CD values and a plurality of LOFO values, wherein the relationship is a measurement grid, wherein the measurement grid comprises a plurality of intersecting grid points, wherein a first axis of the measurement grid comprises a first CD value and a second axis of the measurement grid comprises a first LOFO value, and wherein the determining comprises calculating the first CD value dynamically according to a minimum expected CD and a maximum expected CD and calculating the first LOFO value dynamically according to a minimum expected LOFO and a maximum expected LOFO;
• selecting a first intersecting grid point in the measurement grid, wherein the first intersecting grid point comprises the first CD value and the first LOFO value;
• processing the optical signal a first time in a time domain according to a conjugate of the first LOFO value;
• processing the optical signal in a frequency domain according to a conjugate of a phase response due to the first CD value;
• processing the optical signal a second time in the time domain to determine a correlation of the optical signal with a conjugate of a preamble of the optical signal;
• calculating a polarization metric for the optical signal;
• calculating an average of the optical signal in the time domain according to the correlation of the optical signal with the conjugate of the preamble of the optical signal;
• calculating a first final metric for the first intersecting grid point;
• and
• transmitting the CD estimate, the LOFO estimate, and the optical signal to a downstream node in the communications network for processing by the downstream node, wherein the CD estimate and LOFO estimate facilitate processing of the optical signal by the downstream node.