Article
Engineering, Electrical & Electronic
Benedikt Geiger, Eric Sillekens, Filipe Ferreira, Robert Killey, Lidia Galdino, Polina Bayvel
Summary: The performance of a wideband coherent receiver was studied, focusing on the impact of digital pre-distortion, geometric constellation shaping, pilot sequence detection, and the number of sub-channels in the super-channel. A net data rate of 2.36 Tb/s was achieved after transmitting an 8 x 26 GBd DP-GS-256-QAM super-channel over a distance of 75 km using a single 110 GHz electrical bandwidth receiver. The overall improvement in achievable information rate due to digital pre-distortion and tailored geometric constellation shaping was 1.2 bit/4D-sym.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2023)
Article
Engineering, Electrical & Electronic
Akira Kawai, Masanori Nakamura, Minami Takahashi, Takayuki Kobayashi, Yutaka Miyamoto
Summary: In this article, we propose partially frozen (PF) multiple-input multiple-output (MIMO) adaptive equalizers (AEQs). These AEQs can cope with various signal impairments that occur within a transmitter and receiver, such as in-phase/quadrature (IQ) skew and IQ imbalance. By reducing effective degrees of freedom (DOFs) and freezing unnecessary updates, PF MIMO AEQs can track polarization fluctuations efficiently in a dynamic environment, increasing the information rate of transmissions. Numerical simulations and experiments demonstrate the effectiveness of PF MIMO AEQs in high-speed data transmissions.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2023)
Article
Optics
Hongyu Huang, Zhenming Yu, Liang Shu, Kaixuan Sun, Feifei Yin, Kun Xu
Summary: In this paper, a joint shaping technique combining probabilistic shaping and error feedback noise shaping is proposed and experimentally demonstrated for the first time to improve the performance of a low-resolution transmission system. The results show that using this joint shaping technique, a bit-error-rate of 3.8 x 10-3 can be achieved with a physical number of bits of 3 in the 40-Gbaud IM/DD experimental transmission system. In the 30-Gbaud DP coherent experimental transmission system, a BER below 1 x 10-3 is easily obtained using a 3-bit quantizer with joint shaping. The optimization of the shaping degree is also analyzed.
CHINESE OPTICS LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Christian Dorize, Sterenn Guerrier, Elie Awwad, Haik Mardoyan, Jeremie Renaudier
Summary: In the past decade, coherent technology has been developed for transmission over core optical networks, leveraging fiber capacity through the use of polarization diversity I/Q modulation and advanced signal processing. Recently, Distributed Acoustic Sensing (DAS) over telecom infrastructure has gained interest, and this paper shows that the combination of coherent solutions and digital processing techniques in current transceiver systems can greatly improve DAS technology by enhancing key performance parameters and coexistence with data traffic.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2023)
Article
Engineering, Electrical & Electronic
Takeo Sasai, Etsushi Yamazaki, Yoshiaki Kisaka
Summary: This paper presents analytical results on different methods for estimating the longitudinal power profile in optical fibers at a coherent receiver. The two types of methods reviewed and analyzed are correlation-based methods (CMs) and minimum-mean-square-error-based methods (MMSEs). The paper provides analytical expressions for their output power profiles and spatial resolution, clarifying the theoretical performance limits and differences between the two methods. The study shows that the estimated power profiles of CMs are limited in spatial resolution and measurement accuracy, while MMSEs approach a true power profile under a fine spatial step size, canceling out the convolution effect.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2023)
Article
Engineering, Electrical & Electronic
Vinod Bajaj, Fred Buchali, Mathieu Chagnon, Sander Wahls, Vahid Aref
Summary: This paper details a neural network-based digital pre-distortion technique that aims to mitigate issues faced by high-symbol-rate coherent optical transceivers at high frequency. Through comparisons with other techniques, the study found that this technique performs well in improving signal-to-noise ratio and achieving high-speed transmission.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
Article
Engineering, Electrical & Electronic
Yuchuan Fan, Xiaodan Pang, Aleksejs Udalcovs, Carlos Natalino, Lu Zhang, Vjaceslavs Bobrovs, Richard Schatz, Xianbin Yu, Marija Furdek, Sergei Popov, Oskars Ozolins
Summary: This article evaluates the tolerance of a developed EVM estimation scheme against various impairments in coherent optical systems. The proposed scheme uses deep learning techniques to extract signal quality information. The results show good generalization of the scheme, providing a valuable reference for developing next-generation intelligent OPM systems.
IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS
(2022)
Article
Engineering, Electrical & Electronic
Dawei Wang, Meng Qiao, Kunjian Lian, Zhaohui Li
Summary: Timing recovery is crucial in digital coherent communication systems to synchronize clocks. This involves accurately determining the current sampling error of the local digitizer so that the timing circuit can operate stably. Conventional timing phase detectors need to adapt to the optical fiber channel and understand the effects of chromatic dispersion and polarization mode dispersion on timing phase extraction. By exploiting the cyclostationarity of the optical signal, we derive a model that considers these effects and prove the effectiveness of a CD-adjusted cyclic correlation matrix as a timing phase detector immune to both CD and PMD. Our analysis is validated through simulations and experiments with an optical cable.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2023)
Article
Engineering, Electrical & Electronic
Mark Pelusi, Takayuki Kurosu, Takashi Inoue, Shu Namiki
Summary: This paper evaluates the benefits of Brillouin amplification in coherent communication applications using 64-QAM signals. By utilizing the narrow gain bandwidth, it enhances the carrier to noise ratio (CNR) of noisy spectral lines, resulting in improved performance for signal carriers and pilot tones.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
Article
Engineering, Electrical & Electronic
Xiang Lin, Shenghang Luo, Sunish Kumar Orappanpara Soman, Octavia A. Dobre, Lutz Lampe, Deyuan Chang, Chuandong Li
Summary: This study proposes a machine learning-based scheme to mitigate the intra-channel optical fiber nonlinearity. The scheme utilizes perturbation treatment and a deep neural network to improve performance. Numerical simulations demonstrate the superiority of the proposed scheme over other methods.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
Article
Engineering, Electrical & Electronic
Xianqing Jin, Wei Jin, Zhuqiang Zhong, Shan Jiang, Sujan Rajbhandari, Yanhua Hong, Roger Philip Giddings, Jianming Tang
Summary: This article introduces an improved iterative algorithm for digitally linearizing IMDD transmission systems to reduce signal interference caused by nonlinear operations and improve transmission performance. Experimental results show that the algorithm has a good effect on supporting high-speed transmission and reducing power loss.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
Article
Engineering, Electrical & Electronic
Qun Zhang, Yanfu Yang, Chao Gu, Yong Yao, Alan Pak Tao Lau, Chao Lu
Summary: The proposal introduces a dual-polarization transceiver imbalance monitoring scheme for coherent systems using square QAM signals, with technical advantages of multi-dimensionality, wide monitoring range, and modulation-format transparency. The scheme involves a polarization scrambler and DSP modules for monitoring imbalances between transmitter and receiver through coherent detection.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2021)
Letter
Engineering, Electrical & Electronic
Satoshi Shimizu, Ryohei Kamikawa, Yuta Kaihori, Yu Yamasaki, Tsuyoshi Konishi
Summary: The experimental method demonstrated in this study involves dividing a broad band optical comb into fragments of spectra which are then individually detected and unified based on boundary conditions. The time domain waveform retrieved from these fragments matched well with observations made by a sampling oscilloscope. Results showed good agreement when comparing the amplitude and phase of the optical comb observed through signal-shot and retrieving method.
IEICE ELECTRONICS EXPRESS
(2021)
Article
Engineering, Electrical & Electronic
Peng Li, Zheng Dai, Lianshan Yan, Jianping Yao
Summary: A microwave photonic link with quadrupled capacity based on coherent detection and digital phase noise cancellation is proposed and experimentally demonstrated. By performing intensity modulation at the transmitter and coherent detection at the receiver, as well as applying a digital phase noise cancellation algorithm, high-quality microwave signal transmission is achieved.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
Article
Optics
Honghang Zhou, Yan Li, Wei Li, Jifang Qiu, Xiaobin Hong, Hongxiang Guo, Yong Zuo, Jian Wu
Summary: This work investigates the impact of enhanced hard decision (HD) based on multi-dimensional basis expansion on the performance of PAM4 systems, and validates it experimentally. After 30 km fiber transmission, HD with 2-dimensional basis expansion achieves more reliable transmission compared to traditional HD, while HD with 3-dimensional and 5-dimensional basis expansion further improves system sensitivity.
OPTICS COMMUNICATIONS
(2021)
Article
Engineering, Electrical & Electronic
Md Saifuddin Faruk, Xiang Li, Derek Nesset, Ivan N. Cano, Albert Rafel, Seb J. Savory
Summary: Coherent optics is expected to be the logical choice for the physical layer in future passive optical networks, as intensity-modulation/ direct-detection technology will not meet the power budget requirements for high line-rate systems. The necessity, timeframe, and technological challenges of utilizing coherent technology in future passive optical networks are discussed in this article.
IEEE COMMUNICATIONS MAGAZINE
(2021)
Article
Optics
Josh W. Nevin, Sam Nallaperuma, Nikita A. Shevchenko, Xiang Li, Md. Saifuddin Faruk, Seb J. Savory
Summary: The passage discusses the importance of machine learning in optical networks for extracting data information, planning monitoring, and dynamic control. It mentions various promising avenues for machine learning applications, including explainable machine learning and various methods based on the physical layer and network layer.
Article
Optics
Nikita A. Shevchenko, Sam Nallaperuma, Seb J. Savory
Summary: This paper thoroughly examines the maximized information rates of ultra-wideband lumped-amplified fiber-optic communication systems. It proposes three strategies to maximize point-to-point link throughput and emphasizes the possibility of approaching optimal system performance through pragmatic engineering sub-optimal optimization strategies.
Article
Engineering, Electrical & Electronic
Xiang Li, Md Saifuddin Faruk, Seb J. Savory
Summary: In this letter, a bidirectional symmetric 100 Gb/s/lambda coherent passive optical network (PON) scheme with a simplified optical network unit (ONU) transceiver is proposed and experimentally demonstrated. The proposed scheme achieves a power budget of more than 30 dB for both downstream and upstream signals at 100 Gb/s/lambda, showcasing its potential for high-speed optical communication.
IEEE PHOTONICS TECHNOLOGY LETTERS
(2022)
Article
Computer Science, Hardware & Architecture
Josh W. Nevin, Sam Nallaperuma, Nikita A. Shevchenko, Zacharaya Shabka, Georgios Zervas, Seb J. Savory
Summary: This study introduces a novel application of reinforcement learning with invalid action masking and a new training method for routing and wavelength assignment in fixed-grid optical networks. The efficacy of RL agent is improved by embedding domain knowledge and constraining action space. The proposed approach outperforms standard RL and three state-of-the-art heuristics for the RWA problem in fixed-grid networks.
JOURNAL OF OPTICAL COMMUNICATIONS AND NETWORKING
(2022)
Article
Engineering, Electrical & Electronic
F. J. Vaquero-Caballero, D. J. Ives, S. J. Savory
Summary: This paper proposes a new method for the separation of noise categories based on Four-Wave Mixing. By introducing perturbations, the behavior of different noise categories can be separated. The estimation of noise categories is discussed from the perspective of NSR evolution and power spectral density.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
Article
Computer Science, Hardware & Architecture
Pablo Torres-Ferrera, Frank Effenberger, Md Saifuddin Faruk, Seb J. Savory, Roberto Gaudino
Summary: This article discusses the recent evolution of passive optical network standards and the related research activities for achieving bit rates higher than 10 Gbps per wavelength. The introduction of advanced digital signal processing technologies is identified as a key factor for achieving higher bit rates such as 50, 100, and 200 Gbps per wavelength. The article provides a detailed review of the current standardization activities and compares the digital signal processing approaches for traditional direct detection solutions and future coherent detection approaches.
JOURNAL OF OPTICAL COMMUNICATIONS AND NETWORKING
(2022)
Article
Optics
Zelin Gan, Xiang Li, Seb J. Savory
Summary: In this paper, a nonlinearity-tolerant sphere shaping method based on the parallel bisection structure is proposed. It achieves lower energy and rate loss by selecting preferential sequences. The method mitigates fiber nonlinearity by reducing energy variation, resulting in improved signal-to-noise ratio and information rate.
Article
Engineering, Electrical & Electronic
Andrew Lord, Seb J. Savory, Massimo Tornatore, Abhijit Mitra
Summary: This article summarizes research in areas such as wavelength routing optimization, real-time monitoring, and multiband or multiple fiber connectivity to present a comprehensive view of how future optical networks will support the traffic demands of broadband, 5G, and associated applications.
PROCEEDINGS OF THE IEEE
(2022)
Article
Engineering, Electrical & Electronic
Istvan Bence Kovacs, Md. Saifuddin Faruk, Seb J. Savory
Summary: We demonstrate 200 Gb/s/lambda down-stream transmission for a passive optical network (PON) using a minimal coherent receiver at the optical network unit (ONU). The low complexity receiver at the cost-sensitive ONU employs heterodyne detection and requires a single photodiode, a 3-dB optical coupler, and a local oscillator, making it the simplest coherent receiver. At the optical line terminal (OLT), digital pre-emphasis and Alamouti coding are applied to the 50 GBaud signal. An experimental power budget of 29 dB is achieved, which increases to 34.5 dB with a balanced receiver.
IEEE PHOTONICS TECHNOLOGY LETTERS
(2023)
Article
Computer Science, Hardware & Architecture
Sam Nallaperuma, Zelin Gan, Josh Nevin, Mykyta Shevchenko, Seb J. Savory
Summary: This study proposes a generalized reinforcement learning (RL) model for multi-objective performance optimization in optical networks. Two multi-objective variants of the routing and wavelength assignment (RWA) problem are derived and solved using this model. The optimized route and wavelength are determined based on the number of accepted services, number of transmitters, and network availability. The resulting approximated Pareto front provides decision-making solutions for network operators. These findings contribute to network design and growth, as well as demonstrate the effectiveness of RL in dynamic settings and generalizability for unseen traffic.
JOURNAL OF OPTICAL COMMUNICATIONS AND NETWORKING
(2023)
Proceedings Paper
Engineering, Electrical & Electronic
Md Saifuddin Faruk, Xiang Li, Seb J. Savory
Summary: We demonstrate 100- and 200-Gb/s/lambda line-rate PON downstream transmission using a single-polarization heterodyne receiver with Alamouti-coded 16QAM signal. The power budget for both single-ended and balanced detection is experimentally evaluated considering a 25 km reach.
2022 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC)
(2022)
Proceedings Paper
Engineering, Electrical & Electronic
Xiang Li, Md Saifuddin Faruk, Seb J. Savory
Summary: This paper discusses different nonlinear impairments in short-reach fiber transmission systems, and summarizes recent progress on nonlinear digital signal processing techniques to mitigate such nonlinear impairments.
2021 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXPOSITION (OFC)
(2021)
