Júlio César Medeiros Diniz

Application of Machine Learning Techniques for Amplitude and Phase Noise Characterization

In this paper, tools from machine learning community, such as Bayesian filtering and expectation maximization parameter estimation, are presented and employed for laser amplitude and phase noise characterization. We show that phase noise estimation based on Bayesian filtering outperforms conventional time-domain approach in the presence of moderate measurement noise. Additionally, carrier synchronization based on Bayesian filtering, in combination with expectation maximization, is demonstrated for the first time experimentally.

Machine Learning Techniques for Optical Performance Monitoring From Directly Detected PDM-QAM Signals

Linear signal processing algorithms are effective in dealing with linear transmission channel and linear signal detection, whereas the nonlinear signal processing algorithms, from the machine learning community, are effective in dealing with nonlinear transmission channel and nonlinear signal detection. In this paper, a brief overview of the various machine learning methods and their application in optical communication is presented and discussed. Moreover, supervised machine learning methods, such as neural networks and support vector machine, are experimentally demonstrated for in-band optical signal to noise ratio estimation and modulation format classification, respectively. The proposed methods accurately evaluate optical signals employing up to 64 quadrature amplitude modulation, at 32 Gbd, using only directly detected data.

Flexible optical transmission systems for future networking

This paper describes the path for future implementations of flexible optical transmission. The baseline discussion is divided into the transponder technical aspects and the network subsystem elements. Regarding flexible transponder, three degrees of freedom such as modulation format, symbol rate and number of channels are exploited in order to obtain rate adaptive transmitters and receivers. In addition, digital signal processing is discussed to relax the hardware resources and to enhance transmission performance. As far as the optical networking is concerned, some functionalities present in node subsystems as optical amplifiers and filters in reconfigurable optical add/drop multiplexers (ROADM) / wavelength selective switches (WSS) are optimized and implemented to support the requirements needed in software defined networks (SDN).

Bayesian filtering for phase noise characterization and carrier synchronization of up to 192 Gb/s PDM 64-QAM

We show that phase noise estimation based on Bayesian filtering outperforms conventional time-domain approaches in the presence of moderate measurement noise. Additionally, carrier synchronization based on Bayesian filtering, in combination with expectation maximization, is demonstrated for the first time experimentally.

Experimental investigation and digital compensation of DGD for 112 Gb/s PDM-QPSK clock recovery.

For the first time, the impact of DGD on clock recovery for 112Gb/s PDM-QPSK is experimentally investigated and quantified. We propose and experimentally demonstrate novel digital adaptive timing error detector which is robust to DGD

Enhanced digital polarization demultiplexation via CMA step size adaptation for PM-QPSK coherent receivers

Fixed step size CMA can exhibit serious penalties due to rapid channel variations during coherent receiver polarization demultiplexing. We propose and experimentally demonstrate two CMA gain adaptation methods that improve dynamic equalizer tracking and convergence.

Parameter selection in optical networks with variable-code-rate transceivers

Future flexible transceivers will be able to adjust modulation format, symbol rate and FEC scheme according to the channel and network conditions. This paper uses a combination of theoretical derivations and experimental results to recommend the best set of parameters to satisfy a specific demand to be routed along the network. In particular, for a given required OSNR (which is related to reach) and desired net bit rate, and assuming a capacity-achieving FEC scheme, the paper provides the set of modulation format, symbol rate and code rate which requires the minimum bandwidth, while offering an arbitrarily low bit error rate. We observed that optimum operating points required FEC schemes with overheads ranging from almost 0 to 100%, which is an important guideline for future flexible optical communications systems.

100G and beyond: optical transmission activities in Brazil

Recent advances in high speed optical transmission from 100 Gb/s up to 1Tb/s per channel based on advanced modulation formats in progress in Brazil (CPqD) are exhibited. Optical transmission experimental results of 112G DP-QPSK WDM transmission, 224G DP-16QAM transmission with pre-filtering (achieving 8.96 b/s/Hz), and comb generation optimization for future Co-OFDM transmission are detailed. Digital signal processing set of algorithms built in-house for off-line processing are presented.

448 Gb/s Dual-Carrier PDM-RZ-16QAM on 75-GHz Grid over 720 km with 10 Flexi-Grid ROADM passes

We show 448 Gb/s transmission of dual-carrier pre-filtered PDM-RZ-16QAM modulation in 75-GHz flexi-grid channel spacing over 720 km and 10 ROADM passes with 5.97-b/s/Hz spectral efficiency.

112 Gb/s DP-QPSK coherent optical transmission over 3000 km using an complete set of digital signal processing algorithms

Digital signal processing is a key feature in coherent dual polarization QPSK optical transmission, and plays an essential role to determine system performance. In this paper, we present a set of signal processing algorithms able to recover a single channel 112 Gb/s DP-QPSK signal after 3000 km propagation in a recirculation loop. The OSNR resilience and optical filtering impact over maximum reached distance were also investigated.