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Published on: February 6, 2014
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Frequency-offset-tolerant optical frequency comb-based coherent transmission for intra-datacenter interconnections.
Optics Express
|June 22, 2021
Summary
This study introduces an optical frequency comb (OFC) architecture for data center interconnects, significantly improving frequency offset tolerance in wavelength division multiplexing (WDM) systems. This innovation enhances scalability and reduces costs for high-capacity optical communication.
Area of Science:
- Optical Communications
- Data Center Interconnects
- Signal Processing
Background:
- Increasing demand for intra-datacenter (DC) transmission capacity and scalability necessitates cost-effective solutions for wavelength division multiplexing (WDM).
- Discrete lasers in current WDM systems present limitations in cost and scalability for intra-DC applications.
- Optical Frequency Comb (OFC) sources offer a promising alternative for high-capacity optical transmission.
Purpose of the Study:
- To propose and evaluate a novel OFC-based coherent architecture for intra-DC WDM transmission.
- To demonstrate enhanced frequency offset (FO) tolerance and reduced analog-to-digital converter (ADC) sampling rate requirements.
- To validate the performance through extensive simulations and back-to-back experiments.
Main Methods:
- An OFC-based coherent architecture where the OFC at the receiver is split to serve as local oscillators (LOs).
- Utilizing a splitter with a uniform power ratio to distribute the LO-OFC signals.
- Simulating a coherent WDM transmission system with a 3-tone-OFC for carriers and an 11-tone-OFC for LOs, employing 64GBd polarization multiplexing 16 quadrature amplitude modulation (PM-16QAM).
Main Results:
- Simulations show significant FO tolerances of up to ±0.3THz and ±0.374THz for 64GBd PM-16QAM WDM transmission, below a pre-Forward Error Correction (FEC) bit error rate (BER) of 1.25×10-2.
- The maximum FO tolerance increases linearly with the number of effective tones in the LO-OFC.
- Experiments confirm FO tolerance exceeding 36GHz for 36GBd PM-16QAM with a 3-tone-LO-OFC, below the 1.25×10-2 BER threshold.
Conclusions:
- The proposed OFC-based coherent architecture effectively handles large frequency offsets in intra-DC interconnections.
- This architecture offers a promising solution for high-capacity, scalable, and cost-effective WDM transmission within data centers.
- The system achieves comparable ADC sampling rates to systems without FO, simplifying implementation.
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