Chromatic dispersion mitigation using a SEFDM-based diversity technique for IM/DD long reach optical links

Area of Science:

• Optical Communications
• Signal Processing
• Fiber Optics

Background:

• Orthogonal frequency division multiplexing (OFDM) is a standard in optical communications.
• Higher spectral efficiency (SE) is crucial for beyond 100-Gb/s optical intensity modulation and direct detection (IM/DD) long reach (LR) applications.
• Chromatic dispersion (CD) significantly impacts signal quality in IM/DD LR links.

Purpose of the Study:

• To propose a novel diversity technique for spectral efficient frequency division multiplexing (SEFDM).
• To enhance the performance of SEFDM in beyond 100-Gb/s IM/DD LR optical transmission systems.
• To improve tolerance to power fading caused by chromatic dispersion.

Main Methods:

• Mathematical demonstration of reusing self-created inter-carrier interference (ICI) in SEFDM for diversity gain.
• Implementation of a diversity technique based on SEFDM for optical IM/DD LR links.
• Experimental validation using a 112-Gb/s SEFDM transmission over 80-km standard single-mode fiber with 16-QAM.

Main Results:

• The proposed SEFDM diversity technique effectively reuses ICI to achieve diversity gain on each sub-carrier.
• A 112-Gb/s SEFDM transmission was successfully demonstrated over 80-km standard single-mode fiber using only 28-GHz bandwidth.
• SEFDM with the diversity technique showed superior robustness against CD effects compared to conventional OFDM.

Conclusions:

• The proposed SEFDM diversity technique significantly improves tolerance to chromatic dispersion in IM/DD LR links.
• SEFDM with the diversity technique outperforms conventional OFDM for high-speed optical transmissions.
• This approach validates the superiority of SEFDM for future optical IM/DD LR applications.