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Transmission of Multiple Signals through an Optical Fiber Using Wavefront Shaping

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Published on: March 20, 2017

Ultra-high-order QAM modulation approach based on local constellation decomposition joint shaping.

Ying Zhang, Jiaqi Wang, Wenxiang Yao

|December 19, 2025

Summary

This summary is machine-generated.

This study introduces a novel joint shaping scheme for ultra-high-order Quadrature Amplitude Modulation (QAM) signals, improving bit error rate (BER) performance in intensity modulation direct detection (IMDD) systems using Delta-sigma modulation (DSM). The method enhances receiver sensitivity and system efficiency.

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Area of Science:

Optical Communications
Signal Processing
Digital Communications

Background:

Ultra-high-order Quadrature Amplitude Modulation (QAM) is crucial for increasing data rates.
Existing methods face challenges in efficiently shaping complex constellations for Intensity Modulation Direct Detection (IMDD) systems.
Probabilistic Shaping (PS) and Geometric Shaping (GS) are advanced techniques for constellation optimization.

Purpose of the Study:

To propose and evaluate a local constellation decomposition joint shaping scheme for ultra-high-order QAM signals.
To enhance the transmission performance of 16384QAM in IMDD systems using Delta-sigma modulation (DSM).
To investigate the impact of information entropy on bit error rate (BER) and receiver sensitivity.

Main Methods:

A joint shaping scheme involving global probabilistic shaping (PS), local constellation decomposition, and local geometric shaping (GS).
Integration of Delta-sigma modulation (DSM) for transmitting ultra-high-order 16384QAM signals.
Performance evaluation through simulations under varying information entropy levels and experimental validation over 25 km single-mode fiber (SMF).

Main Results:

The proposed joint shaping scheme with DSM significantly outperforms conventional 16384QAM with DSM for the same information entropy.
Experimental validation confirms the effectiveness of the approach in ultra-high-order communication systems.
Receiver sensitivity improves by approximately 0.6 dB for every 1 bit/symbol reduction in information entropy.

Conclusions:

The local constellation decomposition joint shaping scheme offers a superior method for optimizing ultra-high-order QAM signals in IMDD systems.
The integration of PS, GS, and DSM effectively enhances BER performance and receiver sensitivity.
This approach represents a significant advancement for future high-capacity optical communication systems.