Optical coherent transmission with spectral efficient modulation and detection based on the non-linear Fourier transform
Final Report Abstract
The importance of fiber optical communications as the key technology to carry almost the entire global data traffic can hardly be overstated. The demand for data transmission capacity is growing steadily, but state-of-the-art fiber optical systems may ultimately not be able to keep up with this growing demand. When higher data rates want to be achieved by higher signal transmission power, a nonlinear distortion effect appears along the fiber, that classical transmission systems are not designed to cope with. Thus, new transmission systems are required that take these nonlinearities into account. One possible approach is nonlinear Fourier transform (NFT) based communications. Such systems are inherently not limited by the nonlinear distortions along the fiber link, however their are many challenges for practical implementation. Foremost, the spectrally efficient data transmission, especially in the presence of unavoidable noise. In this project we analyzed so-called soliton pulses as the carrier of information in such systems. For specific scenarios, we have found optimized pulse shapes and we analytically derived an estimate on their efficiency limit. As an improvement, we further proposed a more efficient data encoding scheme. When investigating the soliton pulses, we have observed a pulse property that motivated the development of a new detection algorithm. Our proposed method allows to reduce the computational complexity of any common data detection scheme at the receiver. We also have proven that the method is robust against inevitable numerical inaccuracies. In classical systems, it is common and relatively easy to double data rates by exploiting two independent polarizations of light. At higher signal powers however, they are not independent anymore and it becomes more challenging to exploit this property. We have discovered and modeled, how the two polarizations interact with each other along a noisy fiber link. We have proposed a precoding scheme that simplifies detection by removing this interaction and therefore allows significantly higher data rates. A simple precoding scheme is proposed that almost removes these correlations. This improves the detection performance and allows much higher data rates with the same reliability. By providing insights into efficient modulation and detection schemes, the results of this project provide a guideline for the future development of nonlinear Fourier transform based communications systems.
Publications
- "On Time-Bandwidth Product of Multi-Soliton Pulses," 2017 IEEE International Symposium on Information Theory (ISIT), Aachen, June 2017
A. Span, V. Aref, H. Bülow and S. ten Brink
(See online at https://doi.org/10.1109/isit.2017.8006490) - "Optimization of Multi-Soliton Joint Phase Modulation for Reducing the Time-Bandwidth Product," VDE 19th ITG-Symposium Photonic Networks, Leipzig, June 2018
A. Span, V. Aref, H. Bülow and S. ten Brink
- "Precoding for Dual Polarization Soliton Transmission," 23rd Opto-Electronics and Communications Conference (OECC), Jeju Island, Korea (South), 2018
A. Span, V. Aref, H. Bülow and S. ten Brink
(See online at https://doi.org/10.1109/oecc.2018.8729945) - "Efficient Precoding Scheme for Dual-Polarization Multi-Soliton Spectral Amplitude Modulation," IEEE Transactions on Communications, vol. 67, no. 11, pp.7604-7615, Aug. 2019
A. Span, V. Aref, H. Bülow and S. ten Brink
(See online at https://doi.org/10.1109/tcomm.2019.2935716) - "Time-Bandwidth Product Perspective for Nonlinear Fourier Transform-Based Multi-Eigenvalue Soliton Transmission," IEEE Transactions on Communications, vol. 67, no. 8, pp.5544-5557, Aug. 2019
A. Span, V. Aref, H. Bülow and S. ten Brink
(See online at https://doi.org/10.1109/tcomm.2019.2913870) - "Successive Eigenvalue Removal for Soliton Spectral Amplitude Estimation," IEEE Journal of Lightwave Technology, vol. 38, no. 17, pp.4708-4714, May 2020
A. Span, V. Aref, H. Bülow and S. ten Brink
(See online at https://doi.org/10.1109/jlt.2020.2994156)
