One-shot pre-equalization scheme based on frequency pilot tones for bandwidth-limited IM/DD DCI transmission

Area of Science:

• Optical communications
• Data center interconnects
• Signal processing

Background:

• O-band intensity modulation and direct detection (IM/DD) is crucial for high-speed data center interconnects (DCIs).
• Bismuth-doped fiber amplifiers (BDFAs) offer advantages over SOAs, but system bandwidth limitation remains a critical bottleneck.
• Existing pre-equalization methods struggle to address high-frequency fading caused by bandwidth constraints.

Purpose of the Study:

• To propose and demonstrate an efficient pre-equalization (pre-Eq) method to compensate for bandwidth limitations in O-band DCI systems.
• To utilize frequency pilot tones (FPTs) for accurate magnitude and phase response characterization.
• To validate the effectiveness of the FPT-based pre-Eq against conventional algorithms.

Main Methods:

• Development of a novel pre-equalization technique using frequency pilot tones (FPTs).
• Single-shot characterization of system magnitude and phase responses.
• Experimental demonstration of 100-GBaud PAM-4 signal transmission over 40-km standard single-mode fiber (SSMF) with a 30 GHz bandwidth limitation.
• Comparison with constant modulus algorithm (CMA)-based pre-equalization.

Main Results:

• The FPT-based pre-Eq method effectively compensates for high-frequency fading.
• Successful transmission of a 100-GBaud PAM-4 signal over 40-km SSMF under significant bandwidth limitation.
• The proposed FPT-based pre-Eq demonstrates superior performance compared to CMA-based pre-Eq.

Conclusions:

• The FPT-based pre-Eq is an efficient solution for overcoming bandwidth limitations in high-speed O-band DCI systems.
• This method offers a significant performance improvement for optical data transmission.
• The technique provides a viable path towards higher data rates in data centers.