Marco Secondini's research while affiliated with Scuola Superiore Sant'Anna and other places
What is this page?
This page lists the scientific contributions of an author, who either does not have a ResearchGate profile, or has not yet added these contributions to their profile.
It was automatically created by ResearchGate to create a record of this author's body of work. We create such pages to advance our goal of creating and maintaining the most comprehensive scientific repository possible. In doing so, we process publicly available (personal) data relating to the author as a member of the scientific community.
If you're a ResearchGate member, you can follow this page to keep up with this author's work.
If you are this author, and you don't want us to display this page anymore, please let us know.
It was automatically created by ResearchGate to create a record of this author's body of work. We create such pages to advance our goal of creating and maintaining the most comprehensive scientific repository possible. In doing so, we process publicly available (personal) data relating to the author as a member of the scientific community.
If you're a ResearchGate member, you can follow this page to keep up with this author's work.
If you are this author, and you don't want us to display this page anymore, please let us know.
Publications (141)
Two photonics-based radio frequency multiplication schemes for the generation of high-frequency carriers with low phase noise are proposed and experimentally demonstrated. With respect to conventional frequency multiplication schemes, the first scheme induces a selective cancelation of phase noise at periodic frequency-offset values, whereas the se...
The performance of different probabilistic amplitude shaping (PAS)techniques in the nonlinear regime is investigated, highlighting its dependence on the PAS block length and the interaction with carrier phase recovery (CPR). Different PAS implementations are considered, based on different distribution matching (DM) techniques—namely, sphere shaping...
To achieve the maximum information transfer and face a possible eavesdropper, the samples transmitted in continuous-variable quantum key distribution (CV-QKD) protocols are to be drawn from a continuous Gaussian distribution. As a matter of fact, in practical implementations the transmitter has a finite (power) dynamics and the Gaussian sampling ca...
We propose two novel techniques to implement sequence selection (SS) for fiber nonlinearity mitigation, demonstrating a nonlinear shaping gain of 0.24 bits/s/Hz, just 0.1 bits/s/Hz below the SS capacity lower bound.
The performance of different probabilistic amplitude shaping (PAS) techniques in the nonlinear regime is investigated, highlighting its dependence on the PAS block length and the interaction with carrier phase recovery. Different PAS implementations are considered, based on different distribution matching (DM) techniques. When carrier phase recover...
In the case of photonics-based radio frequency multiplication, a method for cancelling the phase noise of the generated carrier at adjustable periodic frequency offset values is proposed, theoretically analyzed, and experimentally demonstrated up to 110 GHz frequency generation from sixfold 18.3 GHz multiplication
Constellation shaping is a practical and effective technique to improve the performance and the rate adaptivity of optical communication systems. In principle, it could also be used to mitigate the impact of nonlinear effects, possibly increasing the information rate beyond the current limit dictated by fiber nonlinearity. However, this appealing i...
Constellation shaping is a practical and effective technique to improve the performance and the rate adaptivity of optical communication systems. In principle, it could also be used to mitigate the impact of nonlinear effects, possibly increasing the information rate beyond the current limit dictated by fiber nonlinearity. However, this appealing i...
Several modulation techniques aimed at ensuring high capacity and low latency for next generation of mobile transport networks are discussed. Centralized radio access networks are considered based on WDM transmission to ensure long distance, sufficient number of antenna sites and segregation of heterogeneous connectivity services over the same fibe...
Several strategies for nonlinearity mitigation based on signal processing at the transmitter and/or receiver side are analyzed and their effectiveness is discussed. Improved capacity lower bounds based on their combination are presented.
Although forward error-correction (FEC) coding is an essential part of modern fiber-optic communication systems, it is impractical to implement and evaluate FEC in transmission experiments and simulations. Therefore, it is desirable to accurately predict the end-to-end link performance including FEC from transmission data recorded without FEC. In t...
A novel technique to optimize the input distribution and compute a lower bound for the capacity of the nonlinear optical fiber channel is proposed. The technique improves previous bounds obtained with the additive white Gaussian noise decoding metric.
Although forward error-correction (FEC) coding is an essential part of modern fiber-optic communication systems, it is impractical to implement and evaluate FEC in transmission experiments and simulations. Therefore, it is desirable to accurately predict the end-to-end link performance including FEC from transmission data recorded without FEC. In t...
A novel technique for digital backpropagation (DBP) in wavelength-division multiplexing systems is introduced and shown, by simulations, to outperform existing DBP techniques for approximately the same complexity.
A novel technique for digital backpropagation (DBP) in wavelength-division multiplexing systems is introduced and shown, by simulations, to outperform existing DBP techniques for approximately the same complexity.
In the past years, nonlinear frequency division multiplexing (NFDM) has been investigated as a potentially revolutionary technique for nonlinear optical fiber communication. However, while NFDM is able to exploit the Kerr nonlinearity, its performance lags behind that of conventional systems. In this work, we first highlight that current implementa...
The interaction between carrier phase recovery and probabilistic amplitude shaping (PAS) in the nonlinear regime is investigated. We show that, for sufficiently high signal-to-noise ratio, the first provides the same inter-channel nonlinearity mitigation achieved by short block-length PAS.
Probabilistic amplitude shaping—implemented through a distribution matcher (DM)—is an effective approach to enhance the performance and the flexibility of bandwidth-efficient coded modulations. Different DM structures have been proposed in the literature. Typically, both their performance and their complexity increase with the block length. In this...
Pulse amplitude modulation (PAM) is a widely employed digital modulation format. PAM formats are generally classified as bipolar PAM (BPAM) if using both positive and negative amplitude levels, and unipolar PAM (UPAM) if using only non-negative amplitude levels. While BPAM formats are in principle more energy efficient, they are not compatible with...
The standard solution for short-haul fiber-optic communications is to deploy noncoherent systems, i.e., to modulate and detect only the light intensity. In such systems, the signal is corrupted with optical noise from amplifiers and with thermal (electrical) noise. The capacity of noncoherent optical links has been studied extensively in the presen...
The hierarchical distribution matching (Hi-DM) approach for probabilistic shaping is described. The potential of Hi-DM in terms of trade-off between performance, complexity, and memory is illustrated through three case studies.
Detection strategies and modulation formats designed for the AWGN channel are not well suited to operate in the nonlinear frequency domain. We study some improved detection strategies and investigate the ultimate performance limitations of NFDM systems that map conventional linear modulations on the nonlinear spectrum.
The hierarchical distribution matching (Hi-DM) approach for probabilistic shaping is described. The potential of Hi-DM in terms of trade-off between performance,complexity, and memory is illustrated through three case studies.
Deploying periodic inline chromatic dispersion compensation enables reducing the complexity of the digital back propagation (DBP) algorithm. However, compared with nondispersion-managed (NDM) links, dispersion-managed (DM) ones suffer a stronger cross-phase modulation (XPM). Utilizing per-channel dispersion-managed (CDM) links (e.g., using fiber Br...
Nonlinear distortion experienced by signals during their propagation through optical fibers strongly limits the throughput of optical communication systems. Recently, a strong research focus has been dedicated to nonlinearity mitigation and compensation techniques. At the same time, a more disruptive approach, the nonlinear Fourier transform (NFT),...
After reviewing models and mitigation strategies for interchannel nonlinear interference (NLI), we study its characteristics and coherence properties. Based on this study, we devise an NLI mitigation strategy which exploits the synergic effect of phase and polarization noise compensation (PPN) and subcarrier multiplexing with symbol-rate optimizati...
Nonlinear distortion experienced by signals during their propagation through optical fibers strongly limits the throughput of optical communication systems. Recently, a strong research focus has been dedicated to nonlinearity mitigation and compensation techniques. At the same time, a more disruptive approach, the nonlinear Fourier transform (NFT),...
We correct a formula for the numerical nonlinear Fourier transform in [1]. The conclusions of our work are unchanged.
Deploying periodic inline chromatic dispersion compensation enables reducing the complexity of the digital back propagation (DBP) algorithm. However, compared with nondispersion-managed (NDM) links, dispersion-managed (DM) ones suffer a stronger cross-phase modulation (XPM). Utilizing per-channel dispersion-managed (CDM) links (e.g., using fiber Br...
After reviewing models and mitigation strategies for interchannel nonlinear interference (NLI), we focus on the frequency-resolved logarithmic perturbation model to study the coherence properties of NLI. Based on this study, we devise an NLI mitigation strategy which exploits the synergic effect of phase and polarization noise compensation (PPN) an...
In fiber-optic communications, evaluation of mutual information (MI) is still an open issue due to the unavailability of an exact and mathematically tractable channel model. Traditionally, lower bounds on MI are computed by approximating the (original) channel with an auxiliary forward channel. In this paper, lower bounds are computed using an auxi...
We experimentally demonstrate 50 Gb/s transmission below an uncorrected bit error rate (BER) of 10−3 in the C band over a transmission reach that extends from 0 to 20 km using combined amplitude and phase shift (CAPS) codes. The CAPS signal, which is not required to be specifically dispersion compensated for each reach within the 20 km operating ra...
In this work, we study the performance of polarization division multiplexing nonlinear inverse synthesis transmission schemes for fiber-optic communications, expected to have reduced nonlinearity impact. Our technique exploits the integrability of the Manakov equation—the master model for dual-polarization signal propagation in a single mode fiber—...
Two novel detection strategies for nonlinear Fourier transform-based transmission schemes are proposed. We show, through numerical simulations, that both strategies achieve a good performance improvement (up to 3 dB and 5 dB) with respect to conventional detection, respectively without or only moderately increasing the computational complexity of t...
This paper compares and evaluates a set of non-parametric mutual information estimators with the goal of providing a novel toolset to progress in the analysis of the capacity of the nonlinear optical channel, which is currently an open problem. In the first part of the paper, the methods of the study are presented. The second part details their app...
By exploiting a causality property of the nonlinear Fourier transform, a novel decision-feedback detection strategy for nonlinear frequency-division multiplexing (NFDM) systems is introduced. The performance of the proposed strategy is investigated both by simulations and by theoretical bounds and approximations, showing that it achieves a consider...
A novel decision feedback detection strategy exploiting a causality property of the nonlinear Fourier transform is introduced. The novel strategy achieves a considerable performance improvement compared to previously adopted strategies in terms of Q-factor.
We experimentally transmit 50Gb/s over 20km uncompensated SMF with a conventional DSP-free OOK direct detection receiver, exploiting combined amplitude phase shift codes. A simplified implementation based on analog electronics is also validated at 50Gb/s.
A polarization-division multiplexing (PDM) transmission scheme based on the nonlinear Fourier transform (NFT) is considered. A new dual-polarization processing technique with reduced complexity, providing 1dB performance improvement, is introduced.
A novel decision feedback detection strategy exploiting a causality property of the nonlinear Fourier transform is introduced. The novel strategy achieves a considerable performance improvement compared to previously adopted strategies in terms of Q-factor.
The performance of optical fiber systems based on nonlinear frequency-division multiplexing (NFDM) or on more conventional transmission techniques is compared through numerical simulations. Some critical issues affecting NFDM systems-namely, the strict requirements needed to avoid burst interaction due to signal dispersion and the unfavorable depen...
The impact of temporal broadening induced by dispersion in nonlinear frequency-division multiplexing systems is investigated through simulations. Two techniques are investigated to halve the guard time between symbol bursts and reduce the size of the processing window at the receiver, increasing spectral efficiency and reducing computational comple...
Coherent detection is the usual solution to achieve high bit rate transmission over long distance. However, it requires a local oscillator and energy consuming digital signal processing that make it not suitable for cost and energy sensitive interconnections and short haul links. In these applications, direct detection is the preferred solution and...
The concept and significance of the so called nonlinear Shannon limit is reviewed and its relation to the channel capacity is analyzed from an information theory point of view. It is shown that this is a limit (if at all) holding only for conventional detection strategies. Indeed, it should only be considered as a limit to the information rate that...
In fiber-optic communications, evaluation of mutual information (MI) is still an open issue due to the unavailability of an exact and mathematically tractable channel model. Traditionally, lower bounds on MI are computed by approximating the (original) channel with an auxiliary forward channel. In this paper, lower bounds are computed using an auxi...
Nonlinearity mitigation based on the enhanced split-step Fourier method (ESSFM) for the implementation of low-complexity digital backpropagation (DBP) is investigated and experimentally demonstrated. After reviewing the main computational aspects of DBP and of the conventional split-step Fourier method (SSFM), the ESSFM for dual-polarization signal...
![Figure 1. The past and predicted growth of the total Internet traffic [1].](publication/301895458/figure/fig12/AS:358753745555459@1462544966536/The-past-and-predicted-growth-of-the-total-Internet-traffic-1_Q320.jpg)
br/>
Lightwave communications is a necessity for the information age. Optical links provide enormous bandwidth, and the optical fiber is the only medium that can meet the modern society's needs for transporting massive amounts of data over long distances. Applications range from global high-capacity networks, which constitute the backbone of the in...
A performance comparison among some promising low-complexity modulation formats suitable for optical short reach interconnects is presented. Bit error probability, electrical SNR and optical power penalty for different sets of operational parameters has been investigated through a complete analysis of the behavior of each format. Simulation results...
The performance of nonlinearity-tailored detection for single channel, single span optical fibre systems is studied. Monotonically decreasing bit error rate with transmitted power can be achieved without any nonlinearity compensation.
A modeling tool is presented for pre-FEC BER estimation of PM-QPSK alien wavelength signals. A field trial is demonstrated and used as validation of the tool's correctness. A very close correspondence between the performance of the field trial and the one predicted by the modeling tool has been reported.
We introduce a new numerical method for the computation of the inverse
nonlinear Fourier transform and compare its computational complexity and
accuracy to those of other methods available in the literature. For a given
accuracy, the proposed method requires the lowest number of operations
We present a new perturbative approach to the study of signal-noise
interactions in amplified optical fibers. The approach is based on the
hydrodynamic formulation of the nonlinear Schr\"odinger equation that governs
the propagation of light in the fiber. Our method is discussed in general and
is developed in more details for some special cases, na...
Stochastic digital backpropagation (SDBP) is an extension of digital backpropagation (DBP) and is based on the maximum a posteriori principle. SDBP takes into account noise from the optical amplifiers in addition to handling deterministic linear and nonlinear impairments. The decisions in
SDBP are taken on a symbol-by-symbol (SBS) basis, ignoring a...
Enhanced-SSFM digital backpropagation (DBP) is experimentally demonstrated
and compared to conventional DBP. A 112 Gb/s PM-QPSK signal is transmitted over
a 3200 km dispersion-unmanaged link. The intradyne coherent receiver includes
single-step digital backpropagation based on the enhanced-SSFM algorithm. In
comparison, conventional DBP requires tw...
Resilience to cross-phase modulation (XPM) can be improved by employing multicarrier modulation formats. The impact of the number of subcarriers on the achievable information rate is discussed and a possible XPM compensation strategy is suggested.
Factor graphs and message passing allow the near-automated development of algorithms in many engineering disciplines, including digital communications. This paper gives an overview of their possible use in optical communications.
Sub-Nyquist time frequency packing technique was demonstrated for the first
time in a super channel field trial transmission over long-haul distances. The
technique allows a limited spectral occupancy even with low order modulation
formats. The transmission was successfully performed on a deployed Australian
link between Sydney and Melbourne which...
The problem of evaluating the channel capacity of a nonlinear fiber-optic system is reviewed. After properly defining the nonlinear fiber-optic channel, we consider a few alternative models and discuss their suitability for system design and performance evaluation. It is shown that using an accurate model can allow devising modulation and detection...
Different models for the nonlinear optical fiber channel are compared in terms of accuracy. The regular perturbation, enhanced regular perturbation, and logarithmic perturbation models are considered, and a new model based on the Magnus series expansion is introduced.
Time-frequency packing (TFP) transmission provides the highest achievable
spectral efficiency with a constrained modulation format and detector
complexity. In this work, the application of the TFP technique to fiber-optic
systems is investigated and experimentally demonstrated. The main theoretical
aspects, design guidelines, and implementation iss...
Two different detectors that account for the nonlinear signal-noise interaction in a singlechannel coherent optical link are compared. The results indicate that accounting for the correlation between the samples leads to improved performance over stochastic digital backpropagation.
An enhanced version of the popular split-step Fourier method (SSFM) is presented. When used for digital backpropagation, the enhanced method allows a complexity reduction of up to one order of magnitude with respect to standard SSFM without sacrificing performance.
The impact and possible mitigation of interchannel nonlinearity is investigated in single-polarization wavelength-division multiplexing systems by evaluating, both analytically and by simulation, the achievable information rate for a Gaussian-modulated channel surrounded by Gaussian- or constant-envelope-modulated channels. Different number of chan...
The SDN-based differentiated filter configuration (DFC) is proposed for optical networks. According to DFC, the passband of the filters traversed by the same connection can be configured to different values. Experiments including data and control planes are shown to demonstrate the feasibility of the proposed DFC with a 1 Tb/s super-channel based o...
Next generation optical networks will require high levels of flexibility both at the data and control planes, being able to fit rate, bandwidth, and optical reach requirements of different connections. Optical transmission should be able to support very high rates (e.g., 1 Tb/s) and to be distance adaptive while optimizing spectral efficiency (i.e....
Coherent detection allows for a more effective compensation of transmission impairments in the electrical domain. However, in order to be effective, a detection strategy should be based on an accurate channel model capable of providing sufficiently accurate signal statistics. While in the linear regime such a model is available and linear impairmen...
The logarithmic-perturbation model is employed to design equalization and detection schemes for nonlinear fiber-optic systems, whose parameters are estimated and updated by proper training algorithms. Effective mitigation of intra-and inter-channel nonlinearity is demonstrated.
The logarithmic-perturbation model is employed to design equalization and
detection schemes for nonlinear fiber-optic systems, whose parameters are estimated
and updated by proper training algorithms. Effective mitigation of intra- and
inter-channel nonlinearity is demonstrated.
The impact over system performances of narrowband spectral shaping for time-frequency packed faster than Nyquist Tb/s superchannels is evaluated. Comparison between optical and electrical filtering under the presence of partially overlapping neighbor channels is presented and optimal values for filter bandwidth are determined for different filter p...
The problem of analytical evaluation of the maximum rate at which information can be reliably transmitted on a nonlinear wavelength division multiplexing fiber-optic channel with a given modulation format and detection strategy is addressed. An approximate solution of the nonlinear Schrödinger equation is adopted to obtain an accurate analytical di...
In flexi-grid optical networks, fragmentation of spectrum resources may significantly affect the overall network efficiency. Effective techniques for defragmentation (i.e., re-optimization) are then required to limit the wasting of spectrum resources. However, current defragmentation techniques can only be implemented thanks to the presence of addi...
This paper demonstrates a software-defined code-adaptive Tb/s based on time-frequency packing technique. Enhanced OpenFlow architecture is proposed to set transmission parameters (e.g., code rate) of 1Tb/s. Several transmission reach values are achieved with adaptive code rate.
In flexi-grid optical networks, effective defragmentation (i.e., re-optimization) solutions are required to efficiently exploit network spectrum resources. However, current defragmentation solutions can only be implemented thanks to the presence of additional resources, such as spare extensive transponders. In this study, focusing on optically-ampl...
A simple but accurate analytical model for the fiber-optic channel affected by cross-phase modulation (XPM) is proposed and validated through numerical simulations. The model describes XPM as a time-varying and frequency-selective complex fading, whose impact and statistical properties can be analytically investigated. As an example, the proposed m...
We propose a novel method for signal processing of phase-modulated signals suitable for 100 G coherent systems. By exploiting a single semiconductor optical amplifier Mach-Zehnder interferometer, all-optical selective switching with simultaneous wavelength conversion of bursts of data in the original signal is demonstrated. The operation is suitabl...
A new concept for wavelength independent receiver for low cost and reduced complexity wavelength division multiplexing (WDM) differential quadrature phase shift keying (DQPSK) system is presented. The main idea behind the receiver design is the use of a single optical delay interferometer to demodulate the in-phase (I) and quadrature-phase (Q) comp...
A novel maximum likelihood sequence detection (MLSD) strategy to combat fiber non-linearities is presented and compared to known compensation techniques such as backpropagation.
An innovative integrated all-optical device for 100G coherent systems able to simultaneously perform selective data erasing and wavelength conversion from input data is demonstrated. It enables flexible network resource optimization introducing negligible OSNR penalty.
An efficient defragmentation technique based on optical channel re-tuning is proposed for flexible optical networks. Effective defragmentation with no traffic disruption is achieved without additional spare transponders or re-equalization operations.
