Related Experiment Video
Updated: May 15, 2026
06:42
Generation and Coherent Control of Pulsed Quantum Frequency Combs
Published on: June 8, 2018
Improved two-stage equalization for coherent Pol-Mux QPSK and 16-QAM systems
Chen Zhu1, An V Tran, Simin Chen
1Victoria Research Laboratory, NICTA Ltd, Level 2, Building 193, Electrical and Electronic Engineering, University of Melbourne, Australia. zhuc@student.unimelb.edu.au
Optics Express
|December 25, 2012
Summary
A novel two-stage frequency domain equalization method enhances long-haul optical networks. This blind equalization technique improves performance for QPSK and 16-QAM signals, offering faster convergence and better signal quality.
Area of Science:
- Optical Communications
- Signal Processing
- Telecommunications Engineering
Background:
- Long-haul optical networks require robust equalization techniques to compensate for fiber impairments.
- Polarization-multiplexed (pol-mux) systems using Quadrature Phase Shift Keying (QPSK) and 16-Quadrature Amplitude Modulation (16-QAM) are crucial for high-capacity data transmission.
- Existing equalization methods may face limitations in convergence speed and steady-state performance.
Purpose of the Study:
- To introduce a two-stage blind frequency domain equalization method for coherent pol-mux systems.
- To enable flexible path switching in optical networks through blind chromatic dispersion (CD) parameter prediction.
- To improve polarization de-multiplexing and compensate for residual fiber impairments.
Main Methods:
- A two-stage equalization process: 1) Blind CD parameter prediction and equalization, 2) Frequency-domain multi-modulus algorithm (MMA) equalization.
- Implementation of all algorithms in the frequency domain for reduced complexity.
- Experimental demonstration in an 800-km, 10 Gbaud coherent optical pol-mux system.
Main Results:
- The proposed method achieves error-free transmission for QPSK signals with superior convergence speed compared to the Constant Modulus Algorithm (CMA).
- For 16-QAM signals, the MMA equalizer provides over 1-dB improvement in Q-value compared to CMA.
- Frequency-domain implementation offers potentially the least complexity for pol-mux coherent systems.
Conclusions:
- The developed two-stage blind frequency domain equalization method is effective for long-haul coherent pol-mux systems.
- The MMA equalizer demonstrates significant advantages over CMA in terms of performance and convergence.
- This approach supports advanced optical network functionalities like flexible path switching.
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