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Second-Moment Vliant Load Balancing (sVLB) in optical Data Center networks

IEEE Journal on Selected Areas in communications 2025年第5期43卷 1793-1808页

作者： Guo, Yingxin Ye, Tong Ma, Yaxuan Shanghai Jiao Tong University State Key Laboratory of Advanced Optical Communication Systems and Networks Shanghai China

Although optical circuit switch (OCS) based data center network (DCN) can offer high-bandwidth and low-power consumption interconnection for server blocks, it has slow reconfiguration speed and thus is not well-suited to handling highly bursty traffic. Despite several Valiant load-balancing (VLB) type algorithms designed to mitigate this mismatch, they cause notable residual traffic fluctuation, measured by second moment of traffic rate. This leads to a notable tail distribution of flow completion time (FCT). Thereby, this paper proposes a second-moment VLB (sVLB), leveraging the fact that all optical links from the same source rarely burst simultaneously. Different from previous VLB-type algorithms, sVLB utilizes spare capacity in the DCN for load balancing. Specifically, it offloads the bursty traffic from optical links to other intermediate blocks, employing only spare capacity on temporarily idle optical links, and these blocks subsequently route the bursty traffic to its destination. We introduce an sVLB-based framework, which additionally provides a suitable optical topology for sVLB to work with and a weight-based scheme to assist sVLB in intermediate block selection during bursty traffic offloading. Our qualitative assessment and extensive simulation demonstrate that the sVLB-based framework can smooth out the residual traffic fluctuation, thus outperforming existing strategies in normalized FCT. © 1983-2012 IEEE.

关键词： Interconnection networks (circuit switching)

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Experiment of 2×40Gbd PAM8 MISO-FSO system reinforced by high-speed optical signal coupling and precoder-shaped multi-level polar codes

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optical and Quantum Electronics 2025年第1期57卷 1-18页

作者： Yang, Weiying Liu, Xiaoyu Xiao, Shilin Liu, Zhiyang The State Key Laboratory of Advanced Optical Communication System and Networks Shanghai Jiao Tong University Dongchuan Road Shanghai200240 China

This paper proposes and successfully demonstrates a high-speed optical signal coupling (HS-OSC) of 2x40Gbaud PAM8 with precoder-shaped multi-level polar codes (PS-MLPC) in a gain-oriented multiple-input single-output free space optical (MISO-FSO) system. With the pilot-based correction (PBC), the system gets a multi-path error (MPE) detecting and correcting module, which can minimize the MPE and achieve the gain-oriented HS-OSC. On the other hand, PS-MLPC is deployed in the MISO-FSO system to provide the non-uniform PAM-8 symbols and save the power budget. In the experiment, the PBC module is proven to ensure the HS-OSC process by comparing the captured waveforms. Results in the static FSO channel validate that the bit error rate (BER) of the MISO-FSO system is improved from 4.76×10-3 to below 10-5 and the PS-MLPC PAM-8 saves most 0.85 dB effective signal-to-noise ratio (ESNR). Under turbulent conditions, the gain-oriented MISO-FSO system not only enhances the mean ESNR of about 4.3–5.4 dB but also mitigates the standard deviation of ESNR by 40.6–61.4 %, on which the PS-MLPC provides a Q-factor gain of 1.17–1.64 dB. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024.

关键词： Budget control

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Preamble Design for Joint Frame Synchronization, Frequency Offset Estimation, and Channel Estimation in Upstream Burst-Mode Detection of Coherent PON

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Journal of Lightwave Technology 2025年第9期43卷 4127-4138页

作者： Sun, Yongxin Jiang, Hexun Xu, Yicheng Fu, Mengfan Zhu, Yixiao Yi, Lilin Hu, Weisheng Zhuge, Qunbi Shanghai Jiao Tong University State Key Laboratory of Advanced Optical Communication Systems and Networks Department of Electronic Engineering Shanghai200240 China

Coherent optics has shown significant potential as a viable solution for achieving 100 Gb/s and higher speeds in single-wavelength passive optical networks (PON). However, upstream coherent burst-mode detection is a major challenge in deploying coherent optics in access networks. To accelerate digital signal processing (DSP) convergence with minimal preamble length, we propose a novel burst-mode preamble design based on a constant amplitude zero auto-correlation (CAZAC) sequence. This design facilitates comprehensive frequency-domain estimation of various impairments, including state of polarization, chromatic dispersion and differential group delay, providing overall system response information for the equalization pre-convergence. Additionally, this preamble utilizes the same training unit to jointly achieve three key DSP functions: frame synchronization, frequency offset estimation, and channel estimation. This integration contributes to a significant reduction in the preamble length. The feasibility of the proposed preamble with a length of 400 symbols and corresponding DSP was experimentally verified in a 15 Gbaud coherent system using dual-polarization 16 quadrature amplitude modulation. The experimental results based on this scheme showed a superior performance of the convergence acceleration. © 1983-2012 IEEE.

关键词： Frequency domain analysis

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Performance assessment of octagonal layout based integrated photonic reservoir computing for optical channel equalization

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Optics Express 2025年第7期33卷 15814-15826页

作者： Zuo, Xiaoyan Pei, Li Bai, Bing Bai, Bowen Hu, Zhouyi Wang, Jianshuai Qu, Qi Dong, Fei Institute of Lightwave Technology Beijing Jiaotong University Ministry of Education Key Laboratory of All-Optical Networks and Modern Communication Networks Beijing100044 China Technology Co. Ltd. China State Key Laboratory of Advanced Optical Communications System and Networks School of Electronics Peking University Beijing100871 China Beijing Aerospace Institute for Metrology and Measurement Technology Beijing100076 China

Compared to electronic equalizers, the equalizers based on integrated photonic reservoir computing exhibit the advantages of large bandwidth, short latency, and low power consumption. The existing rectangular reservoir layout employs internal nodes as input and output nodes, leading to inadequate signal exchange and extra noise due to waveguide crossing. We proposed an optical channel equalizer based on an octagonal reservoir layout and verified its equalization ability. The system-level simulation of the proposed layout is conducted to investigate the impact of layout shape, node quantity, input and output port number, and weight algorithm on channel equalization performance in a 25Gbaud 4-level pulse amplitude modulation optical communication system. Results indicate that, within a transmission distance of 5-30 km, the bit error rate (BER) of the equalized signal in the proposed octagonal layout is lower than that of a rectangular layout with the same number of nodes. Specifically, at 5 km, the octagonal layout’s BER is 5 and 10 orders of magnitude lower than the rectangular layout and the feedforward equalizer, respectively. Meanwhile, the best readout algorithm, K-nearest neighbor regression, achieves an equalized BER of 7.012 × 10−14 © 2025 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.

关键词： Pulse amplitude modulation

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Wide-Sense Nonblocking Conditions for Flex-grid OXC-Clos networks

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IEEE Journal on Selected Areas in communications 2025年第5期43卷 1809-1822页

作者： Yao, Yibei Ye, Tong Deng, Ning Shanghai Jiao Tong University State Key Laboratory of Advanced Optical Communication Systems and Networks Shanghai China Great Bay University School of Computing and Information Technology Guangdong China

The emerging high-capacity optical networks make it urgent to design large-scale flexible mesh optical cross-connect (OXC). Though Clos networks are the theory for building scalable and cost-effective switching fabrics, the nonblocking conditions for flex-grid optical Clos networks without wavelength conversion remain unknown. This paper studies the nonblocking conditions for the flex-grid OXC-Clos network, which is constructed from a number of small-size standard OXCs. We first show that a strictly nonblocking (SNB) OXC-Clos network will incur a high cost, as small-granularity lightpaths may abuse central modules (CMs), rendering them unavailable for large-granularity requests due to frequency conflicts. Hence, we propose a granularity differential routing (GDR) strategy, the idea of which is to restrict the set of CMs that can be utilized by the lightpaths of each granularity. Under the GDR strategy, we investigate two system models, called granularity-port binding and unbinding models, and prove the wide-sense nonblocking (WSNB) conditions. We show that the cost of WSNB network is remarkably smaller than that of SNB network, and find that the granularity-port unbinding model can offer more flexible network-bandwidth utilization compared to the binding model, with a slight cost associated with switching fabrics. © 1983-2012 IEEE.

关键词： Cross connections (water distribution)

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Sensitivity enhancement and Faraday Effect Compensation in dual-polarization Fiber Optic Rotational Seismometer 4

Sensitivity enhancement and Faraday Effect Compensation in d...

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4th International Computational Imaging Conference, CITA 2024

作者： Huang, Huimin Zhu, Lanxin Wang, Wenbo Chen, Yanjun Shi, Fangshuo Li, Zhengbin The State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Peking University Beijing100871 China

ISBN: (纸本)9781510688834

Seismology, as a crucial field of Earth science, is dedicated to understanding the internal structure of the Earth and crustal movements. In recent decades, rotational seismometers become increasingly mature, and rotational observations have found wide applications in various fields including natural earthquakes, engineering seismology, and volcano monitoring. With over 40 years of development, IFOGs have advantages such as low cost and fully solid-state, which have been widely applied in various fields, including inertial navigation, earthquake monitoring, precision measurement, and more. Currently, the development and application of high-precision rotational seismometers based on IFOGs have become a highly researched area of interest. In order to further improve the accuracy, it is necessary to study the accuracy degradation problem of high-precision rotational seismometers based on IFOGs in complex environments and explore effective solutions. This paper aims to address the environmental adaptability and sensitivity problem of high-precision rotational seismometers based on IFOGs and proposes a new structure based on polarization multiplexing and dual optic-fiber coils. The experimental results show that the proposed configuration provides up to a 90-fold suppression of magnetic error. The new configuration sensitivity reach 4.2 × 10-8 rad/s/√Hz. This structure provides a new option for constructing rotational seismometers with superior performance and strong environmental adaptability. © 2025 SPIE.

关键词： Seismographs

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Light Source Attacks on CMOS-Based QRNGs 4

Light Source Attacks on CMOS-Based QRNGs

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4th International Computational Imaging Conference, CITA 2024

作者： Zhang, Beibei Li, Lang Xu, Yuehan Wang, Tao Zeng, Guihua State Key Laboratory of Advanced Optical Communication Systems and Networks Shanghai Jiao Tong University Shanghai200240 China

ISBN: (纸本)9781510688834

QRNGs, which leverage quantum mechanical principles to generate random numbers, are widely utilized in information security and cryptography. This paper reviews various QRNG systems and their evolution, with a particular focus on the simple and efficient CMOS-based QRNG system. However, while current random number generation methods ensure randomness, they do not guarantee the security of the generated random numbers, especially in encryption applications. The results demonstrate that an attacker can manipulate the light source to inject attack signals, leading to an increase in the entropy value calculated by legitimate users. This allows the attacker to extract additional entropy information. Notably, the compromised random numbers still pass the NIST randomness tests, indicating a fundamental breach of the system's security. This paper proposes strategies for identifying and defending against such potential attacks, with the aim of enhancing the reliability and security of QRNG systems. © 2025 SPIE.

关键词： CMOS integrated circuits

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Chirp-free hundred-picosecond pulse fiber laser based on carbon nanotubes mode-locker

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Optics Express 2025年第7期33卷 14850-14857页

作者： Li, Weixi Jiang, Kailin Dai, Lilong Huang, Qianqian Zou, Meng Luo, Siyu Chen, Siyu Song, Yingxiong Liu, Yunqi Yan, Zhijun Mou, Chengbo Key Laboratory of Specialty Fiber Optics and Optical Access Networks Shanghai Institute for Advanced Communication and Data Science Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication Shanghai University Shanghai200444 China School of Optical and Electronic Information National Engineering Laboratory for Next Generation Internet Access System Huazhong University of Science and Technology Wuhan430074 China

We demonstrate a narrow bandwidth passively erbium-doped mode-locked fiber laser based on single-wall carbon nanotubes (SWCNTs). The center wavelength is 1546.61 nm. The strong filtering effect and low saturable absorber (SA) modulation depth provide advantages for a long pulse duration of 323 ps. An overall spectral bandwidth of 1.3 GHz (0.01 nm) is measured by the optical heterodyne method, representing the narrowest spectral width based on SWCNT under a single filter structure. The obtained spectral width is very close to the transform-limited bandwidth of 8 pm, indicating that the pulse is chirp-free. Meanwhile, the generation of beat signals reveals the strong coherence between pulses. The repetition frequency of the laser is 7.8 MHz, and the number of longitudinal mode locks is only 166, which is the minimum number of longitudinal mode-locking in passively mode-locked laser based on material SA. At the same time, numerical simulations further support our experimental results and reveal the pulse evolution, providing evidence that SA and filter are the key factors in the generation of chirp-free long pulse. © 2025 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.

关键词： Saturable absorbers

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An adjustment-free laser resonator based on micron-scale corner cube array

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Chinese Physics B 2025年第3期34卷 382-387页

作者： Pengyuan Chang Xinrong Huang Caolei Fu Aiping Liu Duo Pan Zhiyang Wang Jingbiao Chen Institute of Quantum Information and Technology Nanjing University of Posts and TelecommunicationsNanjing 210003China State Key Laboratory of Advanced Optical Communication Systems and Networks Institute of Quantum ElectronicsSchool of ElectronicsPeking UniversityBeijing 100087China Hefei National Laboratory Hefei 230088China

The topic of improving the mechanical stability of external cavity diode lasers(ECDLs)has recently attracted widespread attention and *** use of corner-cube-array(CCA)-based resonators provides a potential solution for this purpose,although continuous oscillation at super large incident angle remains *** this work,we employ the CCA resonator to generate continuous oscillation within±20°angular misalignment of cavity mirror in *** the basis of retroreflection theory,the retroreflectivity of a CCA is analyzed by using optical simulation ***,the experiment verifies the advantage of using a CCA over a plane mirror in laser resonator,thereby providing a promising approach for *** threshold characteristic curves measured at different incident angles in the experiment verify that the CCA possesses an obvious anti-angle misalignment *** research introduces an alternative solution of using CCA resonator instead of parallel plane cavity,thereby realizing an adjustment-free ECDL with enhanced mechanical stability.

关键词： laser resonant cavity corner cube array external cavity diode laser threshold curve

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Fabrication-Tolerant High-Speed 5-Bit Silicon optical True Time Delay Line in the O-Band

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Journal of Lightwave Technology 2025年第9期43卷 4358-4366页

作者： Ni, Ziheng Lu, Liangjun Wang, Yixuan Liu, Yuanbin Chen, Jianping Zhou, Linjie Shanghai Jiao Tong University State Key Laboratory of Advanced Optical Communication Systems and Networks Shanghai Institute for Advanced Communication and Data Science Department of Electronic Engineering Shanghai Key Lab of Navigation and Location Services Shanghai200240 China SJTU-Pinghu Institute of Intelligent Optoelectronics Pinghu314200 China

Fast reconfiguration time on the order of nanoseconds is crucial for microwave photonic beamformers, particularly in 5G/6G wireless communication systems. Most previously reported integrated optical true time delay lines (OTTDLs) exhibit a slow response time of tens of microseconds. In this study, we demonstrate an O-band high-speed 5-bit silicon OTTDL based on fabrication-tolerant electro-optic push-pull optical switches, which exhibit lower phase deviation and reduced insertion loss compared to conventional designs. The rising and falling times are 9 ns and 11 ns for the electro-optic switching, respectively. The insertion loss and crosstalk of our fabrication-tolerant high-speed switch element are 0.66 dB (0.74 dB) and −25.09 dB (−27.41 dB) at the bar (cross) state, respectively, at the wavelength of 1310 nm. For the 5-bit OTTDL, the initial phase variation is only ∼0.10π, which is one-sixth of that observed in the conventional design. Additionally, our proposed OTTDL features a low fiber-to-fiber insertion loss of 8.72 dB and a delay tuning range of 0-313.9 ps. The high-performance, fabrication-tolerant OTTDLs hold significant promise for future applications in fast beamforming. © 1983-2012 IEEE.

关键词： Fiber to the x

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