Residual-carrier-aided coherent-lite receiver for wide-linewidth links using low-complexity DD-ML phase tracking.

Area of Science:

• Optical communications
• Photonics engineering

Background:

• Short-reach optical links face challenges with laser phase noise and complexity.
• Existing coherent receivers require sophisticated components for phase noise mitigation.

Purpose of the Study:

• To demonstrate a novel coherent-lite receiver architecture for short-reach optical links.
• To reduce the complexity and cost of coherent receivers by mitigating laser phase noise.

Main Methods:

• Utilized residual-carrier-based recovery to smooth laser phase noise.
• Implemented a decision-directed maximum-likelihood (DD-ML) tracker, replacing blind phase search (BPS).
• Employed a short 4x1 MIMO configuration without frequency-domain chromatic dispersion compensation.

Main Results:

• Achieved minimum Bit Error Rates (BERs) of 2.2x10^-3 and 1.4x10^-2 in a 90-Gbaud PDM-16QAM transmission over 25-km SSMF.
• Demonstrated effective laser phase noise smoothing and simplified carrier-phase recovery.
• Validated the performance with wide transmitter linewidths (100 kHz and 9 MHz).

Conclusions:

• The residual-carrier-aided coherent-lite receiver simplifies phase noise recovery.
• DD-ML tracking effectively preserves BER while reducing complexity.
• This approach enables cost-effective coherent interconnects suitable for wide-linewidth lasers.