Besma Kalla;Ruben S. Luís;Menno van den Hout;Stefano Gaiani;Daniele Orsuti;Yuta Goto;Georg Rademacher;Benjamin J. Puttnam;Ayumi Inoue;Takuji Nagashima;Tetsuya Hayashi;Alberto Gatto;Paola Parolari;Pierpaolo Boffi;Thomas Bradley;Chigo Okonkwo;Hideaki Furukawa
{"title":"3.74 Exabit/s$cdot$km Transatlantic-Class C+L-Band SDM Transmission Over 8,610 km in a 19-Core Randomly-Coupled Multicore Fiber","authors":"Besma Kalla;Ruben S. Luís;Menno van den Hout;Stefano Gaiani;Daniele Orsuti;Yuta Goto;Georg Rademacher;Benjamin J. Puttnam;Ayumi Inoue;Takuji Nagashima;Tetsuya Hayashi;Alberto Gatto;Paola Parolari;Pierpaolo Boffi;Thomas Bradley;Chigo Okonkwo;Hideaki Furukawa","doi":"10.1109/JLT.2026.3706963","DOIUrl":"https://doi.org/10.1109/JLT.2026.3706963","url":null,"abstract":"We investigate ultra-high-capacity, long-haul and transoceanic-class transmission over a 19-core randomly-coupled multicore fiber with standard cladding diameter. For long-haul distances exceeding <inline-formula><tex-math>$text{1000} ,{text{km}}$</tex-math></inline-formula>, we demonstrate the first petabit-per-second-class transmission with a net throughput of <inline-formula><tex-math>$text{1.15} ,{text{Pb}}/{text{s}}$</tex-math></inline-formula> after <inline-formula><tex-math>$text{1033.2} ,{text{km}}$</tex-math></inline-formula>, maintaining petabit-class capacity up to <inline-formula><tex-math>$text{1808.1} ,{text{km}}$</tex-math></inline-formula>. This was achieved by transmitting polarization-multiplexed (PM)-16-quadrature amplitude modulation wavelength division multiplexed signals, spanning more than <inline-formula><tex-math>$text{71} ,{text{nm}}$</tex-math></inline-formula> of optical bandwidth in the C- and L-bands, over 19 parallel and synchronized recirculating loops through an <inline-formula><tex-math>$text{86.1} ,{text{km}}$</tex-math></inline-formula> span. Using PM-quadrature phase-shift keying, we further demonstrate transoceanic-class transmission up to transatlantic-equivalent distances. We achieve a net throughput of <inline-formula><tex-math>$text{434.6} ,{text{Tb}}/{text{s}}$</tex-math></inline-formula> over <inline-formula><tex-math>$text{8610} ,{text{km}}$</tex-math></inline-formula>, resulting in a record capacity-distance product of 3.74 Eb/s<inline-formula><tex-math>$cdot$</tex-math></inline-formula>km. This is the highest value reported for any optical fiber transmission system and represents a 1.27-fold increase over the previously reported record.","PeriodicalId":16144,"journal":{"name":"Journal of Lightwave Technology","volume":"44 16","pages":"7047-7056"},"PeriodicalIF":5.2,"publicationDate":"2026-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11576570","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148719020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pham Tien Dat;Yuya Yamaguchi;Yuki Yoshida;Atsushi Kanno;Naokatsu Yamamoto;Kouichi Akahane
{"title":"Photonics-Enabled Simultaneous THz Signal Demultiplexing and Downconversion","authors":"Pham Tien Dat;Yuya Yamaguchi;Yuki Yoshida;Atsushi Kanno;Naokatsu Yamamoto;Kouichi Akahane","doi":"10.1109/JLT.2026.3672616","DOIUrl":"https://doi.org/10.1109/JLT.2026.3672616","url":null,"abstract":"Terahertz (THz) signal processing is crucial for enabling key applications in the THz band. However, conventional electronics-based solutions face several limitations, largely due to the limited roll-off characteristics of electronic devices, which make multiplexing and demultiplexing densely THz signals challenging. Photonic technology offers unique advantages, including wide bandwidth, low loss, steep roll-off, and high flexibility. In this paper, we present a photonic approach for simultaneous THz signal reception, demultiplexing, and downconversion by converting multiplexed THz signals into the optical domain and leveraging advanced photonic signal processing. As a proof-of-concept demonstration, we validate the system for millimeter-wave signals in the W band and THz signals in the 300-GHz band, achieving aggregate capacities of 150 Gb/s and 220 Gb/s, respectively. We also discuss the applicability and outlook of the proposed system for key THz-band applications, including multiple radio access, multi-user access networks, and integrated access and backhaul. The proposed system can pave the way for THz communications in 6G and beyond.","PeriodicalId":16144,"journal":{"name":"Journal of Lightwave Technology","volume":"44 16","pages":"6989-6999"},"PeriodicalIF":5.2,"publicationDate":"2026-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148719033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"High-Isolation Free-Space Optical Circulator for High-Capacity Bidirectional Satellite Links","authors":"Takashi Kan;Kensuke Murakami;Akihiko Nishitani;Akira Akasaka;Shota Ishimura;Tomonori Yazaki;Shin Fukuhara;Hidenori Takahashi;Takehiro Tsuritani","doi":"10.1109/JLT.2026.3697503","DOIUrl":"https://doi.org/10.1109/JLT.2026.3697503","url":null,"abstract":"High-capacity satellite free-space optical (FSO) communication systems require effective transmit–receive (Tx–Rx) separation to enable bidirectional operation while handling large power disparities between Tx and Rx signals. Conventional Tx–Rx separation schemes based on spatial, polarization, wavelength, or temporal domains provide high isolation but inherently limit achievable capacity by consuming degrees of freedom that could otherwise be used for signal multiplexing. Optical circulators (CIRs) represent a promising alternative; however, the Tx–Rx isolation of existing devices is insufficient for satellite FSO applications. In this paper, we present the development of a high-isolation free-space optical circulator (FSO-CIR) achieving 90 dB isolation over the 1535–1567 nm wavelength range. We show that Tx–Rx crosstalk (XT) in conventional CIRs originates from back-reflected light generated by internal reflection and scattering, and we provide a quantitative evaluation of this back-reflected light based on both theoretical analysis and experimental measurements. By systematically suppressing these reflections, the proposed FSO-CIR achieves significantly enhanced isolation. Furthermore, we demonstrate a 1-Tb/s bidirectional optical communication experiment using the proposed FSO-CIR and show that the improved isolation enhances demodulation performance in the forward direction under bidirectional operation compared with a conventional CIR. These results indicate the potential of high-isolation FSO-CIRs for future satellite FSO communication systems.","PeriodicalId":16144,"journal":{"name":"Journal of Lightwave Technology","volume":"44 16","pages":"7073-7084"},"PeriodicalIF":5.2,"publicationDate":"2026-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148719052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Compact and High-Performance Dual-Polarization Electro-Optic Nonlinear Activation Functions Using Silicon Microrings","authors":"Pengliang Zhang;Tao Jin;Pengjun Wang;Shixun Dai;Weiwei Chen;Yi Tang;Qiang Fu;Jun Li;Tingge Dai;Jianyi Yang","doi":"10.1109/JLT.2026.3703909","DOIUrl":"https://doi.org/10.1109/JLT.2026.3703909","url":null,"abstract":"In this paper, dual-polarization electro-optic nonlinear activation functions using the subwavelength-grating-assisted racetrack microring and double series-coupled racetrack microring based on parity-time symmetry are proposed, designed, and experimentally characterized. Measurement results show that, the fabricated subwavelength-grating-assisted racetrack microring has an extinction ratio of 19.49 dB in the transverse-electric polarization and an extinction ratio of 20.38 dB in the transverse-magnetic polarization. The threshold power of the measured Sigmoid (ReLU) activation function in transverse-electric (transverse-magnetic) polarization is 0.1 mW. For the MNIST handwritten digit classification task, applying the measured Sigmoid and ReLU activation functions within the convolutional neural network results in validation accuracies of 97.03% and 97.14%. For the fabricated double series-coupled racetrack microring, the measured extinction ratios in transverse-electric and transverse-magnetic polarizations are respectively 32.15 dB and 33.13 dB. Sigmoid and ReLU activation functions in this case show a threshold power of 0.1 mW, and their associated validation accuracies reach 97.79% and 97.73%.","PeriodicalId":16144,"journal":{"name":"Journal of Lightwave Technology","volume":"44 16","pages":"7191-7198"},"PeriodicalIF":5.2,"publicationDate":"2026-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148719100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yi Shi;Jie Chen;Qiren Yan;Chunying Xu;Chuliang Wei
{"title":"High-Fidelity Decoupling of Overlapping Acoustic Events for Enhanced Recognition in Distributed Acoustic Sensing","authors":"Yi Shi;Jie Chen;Qiren Yan;Chunying Xu;Chuliang Wei","doi":"10.1109/JLT.2026.3704814","DOIUrl":"https://doi.org/10.1109/JLT.2026.3704814","url":null,"abstract":"Distributed acoustic sensing (DAS) based on phase-sensitive optical time-domain reflectometry (ϕ-OTDR) has emerged as a crucial technology for continuous, long-distance infrastructure monitoring. However, in real-world deployments, the simultaneous occurrence of multiple vibration sources generates complex acoustic-induced strain overlapping along the optical fiber, severely compromising the perception limits and quantitative recognition accuracy of the sensing network. To address this inherent bottleneck, we propose a novel multi-source signal separation framework, the Multi-Scale Time-Domain Cross-Network (MS-TDCN). By utilizing parallel multi-scale Short-Time Fourier Transform (STFT) encoding paths to overcome the time-frequency resolution trade-off, and integrating adaptive scale-weighting with residual compensation, our method successfully disentangles heavily aliased optical phase signals. Evaluated on real-world outdoor ϕ-OTDR datasets, the MS-TDCN achieves average classification accuracies of 94.0% and 87.6% for dual-source and triple-source tasks, respectively. Compared to existing baseline methods, the proposed framework demonstrates competitive separation fidelity and high parameter efficiency, offering a robust, computationally accessible solution for continuous, real-time quantitative signal processing in advanced lightwave sensing networks.","PeriodicalId":16144,"journal":{"name":"Journal of Lightwave Technology","volume":"44 16","pages":"7300-7310"},"PeriodicalIF":5.2,"publicationDate":"2026-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148718949","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Characterization and Mitigation of Atmospheric Turbulence for Coherent Free-Space Optical Communications Systems","authors":"Douglas McDonald;Raphael Bellossi;Szymon Gladysz","doi":"10.1109/JLT.2026.3680251","DOIUrl":"https://doi.org/10.1109/JLT.2026.3680251","url":null,"abstract":"Free-space optical (FSO) communication systems employing coherent modulation offer high spectral efficiency and improved receiver sensitivity compared to intensity-modulation systems. However, coherent detection is inherently more sensitive to atmospheric turbulence, as degradation of a beam's spatial coherence severely impairs detection efficiency. In this work, we present a detailed characterization of the impact of atmospheric turbulence on coherent FSO links through transmission experiments performed over an 824 m free-space link. By simultaneously measuring turbulence strength and single-mode fibre (SMF) coupled power at the receiver, we evaluate both the statistical and temporal fading behavior of the coherent FSO channel. Building on these measurements, we demonstrate turbulence-resilient coherent communication using 10 Gbit/s 16-QAM over the same link using the pilot-assisted transmission scheme. The performance of the pilot-assisted scheme is compared with that of a fibre–coupled coherent system to assess its effectiveness as a turbulence mitigation strategy. The presented results provide insight into turbulence-impaired coherent FSO channels and inform the design of physical-layer mitigation and signal processing techniques for robust coherent optical wireless communication.","PeriodicalId":16144,"journal":{"name":"Journal of Lightwave Technology","volume":"44 16","pages":"6882-6893"},"PeriodicalIF":5.2,"publicationDate":"2026-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11471020","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148718978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Overcoming Dispersion in Multicore Fiber IM-DD Systems by Pairwise SDM Transmission for High-Speed Edge and Datacenter Networks","authors":"Paikun Zhu;Yuki Yoshida;Kouichi Akahane;Ken-ichi Kitayama;Bahram Jalali","doi":"10.1109/JLT.2026.3682737","DOIUrl":"https://doi.org/10.1109/JLT.2026.3682737","url":null,"abstract":"High-speed yet cost-effective intensity-modulation direct-detection (IM-DD) technology with a multilane architecture serves as an important role for optical interconnects in future edge and datacenter networks, while space division multiplexing (SDM) is emerging as a promising technological candidate for multilane. However, fiber chromatic dispersion (CD) remains a critical performance barrier for IM-DD. Current single-lane CD mitigation approaches are facing bottlenecks in complexity. Joint coding/transmission across multiple lanes, namely pairwise transmission, is an efficient solution to overcome CD. This work is extended from our upgraded invited paper on ECOC 2025 and investigates pairwise transmission over SDM lanes in more detail. We first theoretically quantify the impact of inter-lane CD mismatch on pairwise SDM transmission based on phase-diversity coding, revealing that weakly-coupled multicore fiber (WC-MCF) with minimal inter-lane CD mismatch is beneficial to reduce the required SNR or equalizer complexity in pairwise SDM transmission. Based on the theoretical insights, extensive experiments of C-band IM-DD interconnects via pairwise SDM transmission are performed, including up-to-210 Gbps/lane over 35.5 km WC-MCF and HD-FEC-compliant 120 Gbps/lane over 85.4 km WC-MCF. A record per-lane bitrate-distance product among SDM IM-DD systems is achieved with simple pairwise transceivers and Rx-side linear-only equalizers.","PeriodicalId":16144,"journal":{"name":"Journal of Lightwave Technology","volume":"44 16","pages":"6933-6941"},"PeriodicalIF":5.2,"publicationDate":"2026-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148719021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Giammarco Di Sciullo;Ruben S. Luís;Menno van den Hout;Robert Emmerich;Nicolas Braig-Christophersen;Qi Wu;Benjamin J. Puttnam;Divya A. Shaji;Andrea Marotta;Fabio Graziosi;Antonio Mecozzi;Colja Schubert;Tetsuya Hayashi;Takuji Nagashima;Chigo Okonkwo;Georg Rademacher;Chiara Lasagni;Paolo Serena;Antonino Nespola;Hideaki Furukawa;Cristian Antonelli
{"title":"19.2 THz S+C+L Transmission Over Field-Deployed Coupled-Core Multi-Core Fiber Enabled by Distributed Raman Amplification","authors":"Giammarco Di Sciullo;Ruben S. Luís;Menno van den Hout;Robert Emmerich;Nicolas Braig-Christophersen;Qi Wu;Benjamin J. Puttnam;Divya A. Shaji;Andrea Marotta;Fabio Graziosi;Antonio Mecozzi;Colja Schubert;Tetsuya Hayashi;Takuji Nagashima;Chigo Okonkwo;Georg Rademacher;Chiara Lasagni;Paolo Serena;Antonino Nespola;Hideaki Furukawa;Cristian Antonelli","doi":"10.1109/JLT.2026.3713754","DOIUrl":"https://doi.org/10.1109/JLT.2026.3713754","url":null,"abstract":"We present the transmission of a 19.2 THz-wide signal spanning the S-, C-, and L-bands, over a standard-cladding- diameter, 69.3 km-long coupled-core four-core fiber (CC-4CF), field-deployed in the Italian city of L'Aquila. The transmission of 1540 × 12.25 GBaud spatial super-channels with polarization-division multiplexed (PDM) 256-ary quadrature-amplitude modulation (256QAM), 64QAM, and 4QAM signals, relying on a hybrid amplification scheme integrating lumped amplification and distributed Raman amplification (DRA) with single-core pumping per direction, results in an aggregate throughput of 929.9 Tb/s estimated using generalized mutual information (GMI) and 864.8 Tb/s after forward-error correction (FEC) decoding. Uniformity of the DRA is verified by analyzing the system mode-dependent loss both with and without Raman amplification. Transmission of the same set of signals over a co-deployed 6.3 km-long CC-4CF, omitting Raman amplification, results in an aggregate throughput of 955 Tb/s estimated using GMI and 892.9 Tb/s after FEC-decoding, showing only a 3% improvement compared to the longer fiber link. This highlights the substantial benefit of using DRA to support multi-band wavelength-division multiplexing over coupled-core multi-core fibers (CC-MCFs). This work reports the first demonstration of S+C+L band transmission over standard-cladding-diameter CC-MCFs, the first use of DRA in such fibers, and the highest reported throughput ever achieved over any field-deployed fiber.","PeriodicalId":16144,"journal":{"name":"Journal of Lightwave Technology","volume":"44 16","pages":"7064-7072"},"PeriodicalIF":5.2,"publicationDate":"2026-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11610856","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148718975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}