Transmission of intensity modulation-direct detection signals far beyond the dispersion limit enabled by phase-retrieval

Error-Controlled Iterative Algorithms for Digital Linearization of IMDD-Based Optical Fibre Transmission Systems

“…He is now with College of Science, Chongqing University of Technology, Chongqing 400054, China (e-mail: zqzhong@cqut.edu.cn). Based on the Gerchberg-Saxton (G-S) algorithm for the 2Dimage construction of X-ray diffraction [20], the phase retrieval of 1D signals was developed for CD pre-compensation [21], [22] or post-compensation [23] for improving signal transmission capacities or reaches of non-return-to-zero on-off keying (NRZ-OOK)-encoded IMDD systems [22], [23] and even quadrature phase shift keying (QPSK)-encoded coherent systems [24]. To further improve the capacity versus reach performances of IMDD transmission systems, a decisiondirected data-aided iterative algorithm (DD-DIA) [25] and a multi-constraint iterative algorithm (MCIA) [26] have recently been reported, which support ≥100 Gb/s 4-level pulse amplitude modulation (PAM4) IMDD transmission over ≥50 km SMFs.…”

Data-Aided Iterative Algorithms for Linearizing IM/DD Optical Transmission Systems

“…These techniques include Volterra equalization [7], Tomlinson-Harashima precoding [8] and FDE-MLSE [9]. Regardless of their algorithm complexity, these techniques can support up to 84-Gb/s over 80-km [9] or 56-Gb/s over 100-km [10] optical transmissions at C-band.…”

“…Recently, an iterative field retrieval algorithm originating from the G-S algorithm developed for optical imaging shows good potential for further improving the signal transmission capacity of the IM/DD optical transmission systems. In previously published work, the modified G-S algorithms can be applied at the transmitter [11] and the receiver [10,12] for pre-emphasis and post-compensation, respectively. In the algorithms, the received optical current is regarded as the image plane, and the transmitted optical signal is regarded as the object plane where its phase is determined by pre-determined modulator/system characteristics including the chromatic dispersion parameter, the fiber length and the characteristics of the intensity modulator.…”

Electronic dispersion compensation and functional link neural network equalization for IM/DD links

“…A phase retrieval iterative algorithm, known as Gerchberg-Saxton (GS) algorithm was demonstrated for EDC in IM/DD transmission in both theory [3] and experiment [4], [5]. The iterative GS algorithm fundamentally linearizes the IM/DD channel effect including square-law detection through treating the optical phase after direct detection as degree of freedom, while optimizing the optical amplitude at the transmitter to compensate for both CD induced power fading and nonlinear distortion.…”