The Experts below are selected from a list of 195 Experts worldwide ranked by ideXlab platform
Joschua Dilly - One of the best experts on this subject based on the ideXlab platform.
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Quality-of-Transmission Estimation in Physical Impairment Aware Flexible Optical Networks
arXiv: Signal Processing, 2020Co-Authors: Joschua DillyAbstract:In this thesis the creation of nonlinear interference noise (NLIN) in the context of impairment aware flexible optical networks is investigated to estimate transmission quality. In particular, the nonlinear interference of neighboring channels (interferer) during transmission on a channel under test is studied. The modulation format of the interferer, the Accumulated Chromatic Dispersion of the interferer, the span length and channel spacing are identified as the parameter influencing the generation of NLIN in the context of flexible optical networks. Estimation of the NLIN is done based on the evaluation of numerical simulation results and compared to recent analytical transmission models, namely the Gaussian noise model and the enhanced Gaussian noise model. In addition to nonlinear noise power, the simulations also yield information about the phase- and circular-noise contributions as well as the correlation time of the phase noise. The results are evaluated in the context of the pulse-collision picture and the influence on transmission quality is discussed.
Kun Qiu - One of the best experts on this subject based on the ideXlab platform.
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analogue to digital converter phase insensitive Dispersion search method with large search step size for low computational cost
Iet Communications, 2016Co-Authors: Yun Ling, Kun QiuAbstract:Accumulated Chromatic Dispersion (CD) estimation is crucial for frequency-domain equalisation in an optical coherent digital receiver. To solve the problems of small search step size and analogue-to-digital converter (ADC) sampling phase sensitivity from conventional CD searching algorithm, a CD searching method with modified shift parameters and waveforms is proposed in this study. The modified CD searching method allows a much larger search step size and can achieve faster CD estimation with low computational complexity. The performance of the modified CD searching method is also insensitive to ADC sampling phase. On the basis of simulation results, a very low search error probability is confirmed with a search step size of 50 km. About 1 K symbols are found to be enough for Dispersion estimation. After the frequency-domain equaliser (FDE) with the estimated Dispersion value, the residual Dispersion length <30 km can be well compensated with a 9-tap adaptive time-domain equaliser (TDE) with fast convergence. The overall error rate performance of the tunable electrical Dispersion compensation is also studied and compared with lumped and distributed optical Dispersion compensation for dynamically switched optical networks.
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Analogue-to-digital converter phase insensitive Dispersion search method with large search step size for low computational cost
IET Communications, 2016Co-Authors: Yun Ling, Kun QiuAbstract:Accumulated Chromatic Dispersion (CD) estimation is crucial for frequency-domain equalisation in an optical coherent digital receiver. To solve the problems of small search step size and analogue-to-digital converter (ADC) sampling phase sensitivity from conventional CD searching algorithm, a CD searching method with modified shift parameters and waveforms is proposed in this study. The modified CD searching method allows a much larger search step size and can achieve faster CD estimation with low computational complexity. The performance of the modified CD searching method is also insensitive to ADC sampling phase. On the basis of simulation results, a very low search error probability is confirmed with a search step size of 50 km. About 1 K symbols are found to be enough for Dispersion estimation. After the frequency-domain equaliser (FDE) with the estimated Dispersion value, the residual Dispersion length
Huug de de Waardt - One of the best experts on this subject based on the ideXlab platform.
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maximum likelihood sequence estimation for optical phase shift keyed modulation formats
Journal of Lightwave Technology, 2009Co-Authors: M S Alfiad, D Van Den Borne, F N Hauske, Antonio Napoli, A M J Koonen, Huug de de WaardtAbstract:Electronic Chromatic Dispersion compensation employing maximum-likelihood sequence estimation (MLSE) has recently been the topic of extensive research and a range of commercial products. It is well known that MLSE provides a considerable benefit for amplitude modulated modulation formats such as on-off keying (OOK) and optical duobinary. However, when applied to optical phase modulation formats, such as differential phase-shift keying (DPSK) and differential quadrature phase-shift keying (DQPSK), it has been shown that the benefit is only marginal. This paper investigates joint-decision MLSE (JD-MLSE) detection applied to 10.7-Gb/s DPSK. It demonstrates that a JD-MLSE using the constructive and destructive components preserves the 3-dB optical signal-to-noise ratio (OSNR) advantage of DPSK over OOK in Dispersion-limited optical systems. Furthermore, we demonstrate that the use of a shortened MZDI with MLSE for the 10.7-Gb/s DPSK modulation can equalize an Accumulated Chromatic Dispersion of 4000 ps/nm. In addition, we discuss in this paper different MLSE schemes applied to 2 times 10.7-Gb/s DQPSK modulation. It is shown that a joint-symbol MLSE (JS-MLSE) on the balanced outputs of the in-phase and quadrature components gives the best performance.
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Long-haul DWDM transmission systems employing optical phase conjugation
IEEE Journal of Selected Topics in Quantum Electronics, 2006Co-Authors: S L Jansen, Giok Djan Khoe, S. Spalter, Peter M. Krummrich, Dirk Van Den Borne, Huug de de WaardtAbstract:In this paper, we review the recent progress in transmission experiments by employing optical phase conjugation (OPC) for the compensation of Chromatic Dispersion and nonlinear impairments. OPC is realized with difference frequency generation (DFG) in a periodically poled lithium-niobate (PPLN) waveguide, for transparent wavelength-division multiplexed (WDM) operation with high conversion efficiency. We discuss extensively the principle behind optical phase conjugation and the realization of a polarization independent OPC subsystem. Using OPC for Chromatic Dispersion compensation WDM 40-Gb/s long-haul transmission is described. As well, transmission employing both mixed data rates and mixed modulation formats is discussed. No significant nonlinear impairments are observed from the nonperiodic Dispersion map used in these experiments. The compensation of intrachannel nonlinear impairments by OPC is described for WDM carrier-suppressed return-to-zero (CSRZ) transmission. In this experiment, a 50% increase in transmission reach is obtained by adding an OPC unit to a transmission line using Dispersion compensating fiber (DCF) for Dispersion compensation. Furthermore, the compensation of impairments due to nonlinear phase noise is reviewed. An in-depth analysis is conducted on what performance improvement is to be expected for various OPC configurations and a proof-of-principle experiment is described showing over 4-dB improvement in Q-factor due to compensation of nonlinear impairments resulting from nonlinear phase noise. Finally, an ultralong-haul WDM transmission of 22times20-Gb/s return-to-zero differential quadrature phase-shift keying (RZ-DQPSK) is discussed showing that OPC can compensate for Chromatic Dispersion, as well as self-phase modulation (SPM) induced nonlinear impairments, such as nonlinear phase noise. Compared to a "conventional" transmission link using DCF for Dispersion compensation, a 44% increase in transmission reach is obtained when OPC is emplo- - yed. In this experiment, we show the feasibility of using only one polarization-independent PPLN subsystem to compensate for an Accumulated Chromatic Dispersion of over 160 000 ps/nm
Ping Kong Alexander Wai - One of the best experts on this subject based on the ideXlab platform.
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Simultaneous and Independent OSNR and Chromatic Dispersion Monitoring Using Empirical Moments of Asynchronously Sampled Signal Amplitudes
IEEE Photonics Journal, 2012Co-Authors: F. N. Khan, Alan Pak Tao Lau, Trevor Anderson, Ping Kong Alexander WaiAbstract:We analytically investigate and derive equations for the empirical moments of asynchronously sampled signal amplitudes as functions of signal power, noise power, and Accumulated Chromatic Dispersion (CD) of a transmission link. The solutions of these equations enable low-cost, simultaneous and independent monitoring of in-band optical signal-to-noise ratio (OSNR) and CD of the fiber link for various modulation formats and data rates. Numerical simulations are performed to validate the proposed technique and the results demonstrate independent OSNR and CD monitoring with good accuracy and large monitoring ranges. The influence of first-order polarization-mode Dispersion (PMD) on the accuracy of the proposed monitoring technique is also investigated.
Pierpaolo Boffi - One of the best experts on this subject based on the ideXlab platform.
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Flexible transmitters based on directly modulated VCSELs for next-generation 50G passive optical networks
Journal of Optical Communications and Networking, 2020Co-Authors: Paola Parolari, Alberto Gatto, Christian Neumeyr, Pierpaolo BoffiAbstract:Discrete multitone (DMT) modulation, due to its water-filling nature, is proposed to enable flexibility in passive optical networks (PONs), optimizing the PON resource usage. The use of DMT signals to directly modulate long-wavelength vertical-cavity surface-emitting lasers (VCSELs) can provide energy-efficient transmitters for 50G PONs. First, we present preliminary experimental measures employing both single-sideband and dual-sideband DMT modulation with already available short-cavity VCSELs operating in the third window to study the PON performance as a function of the Accumulated Chromatic Dispersion and of the received power. The experimental results are then compared with simulations, demonstrating the effectiveness of the developed simulation tool. Then we study the performance of DMT-modulated transmitters based on next-generation short-cavity VCSELs with higher bandwidth (up to 20 GHz) operating in the O-band, evaluating their Chromatic Dispersion resilience. Finally, considering the statistics of a commercially deployed PON, we demonstrate that DMT modulation, providing link adaptation, offers a significant increase in the total aggregated capacity compared to a single-carrier-based fixed-rate PON, optimizing the PON resource usage with respect to the available power budget and the Dispersion impairments.
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ICC - Next generation 50G PON flexible transmitters based on directly modulated VCSELs.
ICC 2020 - 2020 IEEE International Conference on Communications (ICC), 2020Co-Authors: Paola Parolari, Pierpaolo Boffi, Alberto Gatto, Christian NeumeyrAbstract:We consider long-wavelength vertical cavity surface emitting lasers (VCSELs) directly modulated with discrete multitone (DMT) signals as a very promising solution for implementing energy-efficient transmitters for 50G passive optical networks (PONs). Two scenarios based on single sideband and dual sideband modulation are taken into account. Preliminary experimentation with already available short-cavity VCSELs operating in the third window is presented to show the PON performance as a function of the Accumulated Chromatic Dispersion and of the received power. Experimental results are also used to validate a simulation tool, which is further used to provide the performance evaluation of transmitters based on next-generation short cavity VCSELs with higher bandwidth (up to 20 GHz), operating in the O band. Thanks to its water-filling nature, DMT is demonstrated to enable PON flexibility: in fact, considering the statistics regarding a commercially deployed PON, a significant increase of the maximum aggregated capacity is provided, optimizing the PON resource usage with respect to the losses and Dispersion impairments.
