Ultra wide-range frequency offset estimation for digital coherent optical receivers
AssigneeNEC Laboratories America, Inc.
InventorsLei Xu, Shaoliang Zhang, Jianjun Yu, Ting Wang
Life of this patent
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Abstract
Methods and systems for receiving an optical signal using cascaded frequency offset estimation. Coherently detecting an optical signal includes compensating for a coarse laser frequency offset between a transmitting laser and a local oscillator laser by determining a maximum phase error (MPE) in the optical signal, compensating for a residual laser frequency offset between the transmitting laser and the local oscillator laser, and decoding data stored in the optical signal.
Claims20
A method for receiving an optical signal, including:
- coherently detecting an optical signal, including:
- compensating for a first laser frequency offset between a transmitting laser and a local oscillator laser by determining a maximum phase error (MPE) in the optical signal;
- and
- compensating for a residual laser frequency offset between the transmitting laser and the local oscillator laser;
- and
- decoding data stored in the optical signal.
A receiver, including:
- a digital signal processor configured to detect an optical signal, including:
- a coarse frequency offset estimator (FOE) configured to compensate for a first laser frequency offset between a transmitting laser and a local oscillator laser by determining a maximum phase error (MPE) in the optical signal;
- and
- a fine FOE configured to compensate for a residual laser frequency offset between the transmitting laser and the local oscillator laser;
- and
- a digital signal processor configured to decode data stored in the optical signal.
A method for receiving an optical signal, including:
- coherently detecting an optical signal, including:
- compensating for a first laser frequency offset between a transmitting laser and a local oscillator laser by:
- determining a maximum phase error (MPE) in the optical signal by sweeping a timing offset;
- converting the MPE to a coarse derotation value by comparing the MPE to a lookup table;
- and
- derotating the signal using the coarse derotation value;
- and
- compensating for a residual laser frequency offset between the transmitting laser and the local oscillator laser by:
- determining a fine derotation value;
- and
- derotating the optical signal using the fine derotation value;
- and
- decoding data stored in the optical signal.
Dependencies are inferred from the claim text.