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Non-Abelian permutations meet D4 group in a four-state non-Hermitian system

Physical Review B 2024年第2期110卷 L020104-L020104页

作者： Linsheng Bao Aoqian Shi Yuchen Peng Peng Peng Jiayun Ning Zhennan Wang Chao Peng Jianjun Liu Key Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education School of Physics and Electronics State Key Laboratory of Advanced Optical Communication Systems and Networks Department of Electronics and Frontiers Science Center for Nano-optoelectronics Greater Bay Area Institute for Innovation

Encircling non-Hermitian exceptional points (EPs) leads to the swapping of eigenstates, which naturally corresponds to the different state permutations. Here, we find that non-Abelian permutations meet the D4 group in a four-state non-Hermitian system. By encircling three different exceptional arcs within a three-dimensional parameter space, we present seven eigenvalue permutations and correlate them with seven nontrivial operations in the non-Abelian D4 group. Furthermore, our theory reveals the topological properties of higher-order EPs, improves the understanding of EPs in non-Hermitian systems, and offers a robust methodology for examining non-Abelian properties in systems with multiple EPs.

关键词： Topological order Non-Hermitian systems Group theory

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Flexible and High-Fidelity Concurrent Dual-Band Delta-Sigma Modulator for Diverse Applications Convergence

Flexible and High-Fidelity Concurrent Dual-Band Delta-Sigma ...

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2023 Asia communications and Photonics Conference/2023 International Photonics and Optoelectronics Meetings, ACP/POEM 2023

作者： Yan, Zijun Zhu, Yixiao Zhang, Yikun Hu, Yimin Lin, Gengming Wu, Qi Cheng, Ziyu Hu, Weisheng Shanghai Jiao Tong University State Key Laboratory of Advanced Optical Communication System and Networks Shanghai China

We propose and experimentally demonstrate a concurrent dual-band delta-sigma modulation for fronthaul. The proposed modulator can flexibly adjust the center frequency of each passband with ~3.0-dB SNR improvement, sup... 详细信息

ISBN: (纸本)9798350312614

关键词： concurrent dual-band delta-sigma modulator flexible passband radio-over-fiber

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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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Receiver Sensitivity Improvement with Joint Geometric and Probabilistic Shaping for 200G Flexible Coherent Passive optical Network

Receiver Sensitivity Improvement with Joint Geometric and Pr...

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2023 Asia communications and Photonics Conference/2023 International Photonics and Optoelectronics Meetings, ACP/POEM 2023

作者： Lin, Gengming Zhu, Yixiao Yan, Zijun Hu, Yimin Chen, Xi Zhuge, Qunbi Hu, Weisheng Shanghai Jiao Tong University State Key Laboratory of Advanced Optical Communication System and Networks Shanghai China

We optimize and experimentally demonstrate joint GPS scheme under level-dependent PD noise for 200G flexible coherent PON. GPS-16-QAM scheme achieves >1-dB and 0.6-dB receiver sensitivity improvement compared with ... 详细信息

ISBN: (纸本)9798350312614

关键词： coherent PON geometric shaping PD noise probabilistic shaping

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optical Multipath Interference Noise Resistant Digital RoF Fronthaul Achieving 15-dB SNR Enhancement Based on Uneven Spacing and Bit Interleaving

Optical Multipath Interference Noise Resistant Digital RoF F...

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2023 Asia communications and Photonics Conference/2023 International Photonics and Optoelectronics Meetings, ACP/POEM 2023

作者： Hu, Yimin Zhu, Yixiao Zhang, Yikun Yan, Zijun Lin, Gengming Cheng, Ziyu Hu, Weisheng State Key Laboratory of Advanced Optical Communication System and Networks Shanghai Jiao Tong University Shanghai China

We demonstrate uneven spacing and bit interleaving schemes to suppress MPI impairment in digital radio-over-fiber system without complicated DSP by protecting the significant quantization bits. Both simulation/experim... 详细信息

ISBN: (纸本)9798350312614

关键词： bit interleaving digital radio-over-fiber multipath interference pulse amplitude modulation uneven spacing

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Revealing of long-range soliton interaction induced time and phase dynamics in a mode-locked fiber laser

Revealing of long-range soliton interaction induced time and...

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作者： Xian, Tianhao Zhan, Li State Key Laboratory of Advanced Optical Communication System and Networks School of Physics and Astronomy Shanghai Jiao Tong University Shanghai200240 China

By means of the dispersive temporal interferometry technique, we carried out a real-time observation of the time separation and relative phase evolutions of two pulses toward harmonic mode-locking. During the separation stage of the buildup process, the time separation increases, while the relative phase decreases synchronously, and the largest change rates are 0.247 fs/r and −0.017 rad/r, respectively. Meanwhile, the two rates show a linear relation with the former 17.4 times larger than the latter. Moreover, a residual phase change rate of −3.89 × 10−4 rad/r is observed in a steady non-uniform dual-soliton state, while such phase change is absent in a uniform four-soliton state. This study unveils the soliton interaction dynamics in lasers, which not only help to reduce timing jitter in multi-soliton mode-locking, but also bring insight to a temporal tweezing of femtosecond pulse. © 2024 Optica Publishing Group.

关键词： Solitons

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Performance Improvement of Adaptive N-Square PS-QAM Based on LUT for Flexible Coherent PON

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Journal of Lightwave Technology 2025年第12期43卷 5569-5578页

作者： Lin, Gengming Zhu, Yixiao Yan, Zijun Cheng, Ziyu Zhuge, Qunbi Hu, Weisheng Shanghai Jiao Tong University State Key Lab of Advanced Optical Communication Systems and Networks School of Electronic Information and Electrical Engineering Department of Electronic Engineering Shanghai200240 China

Flexible coherent passive optical network (PON) is recognized as an advanced capacity optimization strategy for beyond 100G PON due to its flexibility and adaptability, which are pivotal for the evolution of high-capacity optical access networks. In this study, we propose an adaptive N-square QAM scheme compatible with probabilistic shaping (PS), enabling a more continuous variation of shaping entropy compared to standard 2M-QAM shaping scheme and improved frequency offset estimation (FOE) accuracy in blind 4th-power Fast-Fourier-transform (FFT) algorithm. In experimental demonstrations, dynamic-range and data-rate product (DRDRP) of uniform N2-QAM surpasses that of uniform 2M-QAM by 86 dB·Gbps. The DRDRP of PS N2-QAM also outperforms that of PS 2N-QAM by around 41 dB·Gbps. The development of PON optimization scheme for multi-carrier transmission is achieved through the generation of a look-up table (LUT) based on channel signal-to-noise ratio (SNR) conditions. The feasibility of the LUT is demonstrated under different super-Gaussian filter parameter settings at the back-to-back (B2B) scenario. After 20-km standard single-mode fiber (SSMF) transmission, the normalized generalized mutual information (NGMI) is greater than 0.985 across four subcarriers with varying received optical power (ROP) from -16 to -11 dBm. © 2025 IEEE.

关键词： Single mode fibers

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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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Condition Monitoring of Distribution networks Based on Radiated Electromagnetic Signals

Condition Monitoring of Distribution Networks Based on Radia...

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2024 IEEE International Conference on Computational Electromagnetics, ICCEM 2024

作者： Ma, Jie Li, Lianlin School of Electronics Peking University State Key Laboratory of Advanced Optical Communication Systems and Networks Beijing China

ISBN: (纸本)9798350383317

The reliable operation of the distribution network is intricately linked to the overall stability of the power system. However, existing methodologies often fall short in precisely identifying the fault location within the electricity distribution network and providing timely warnings prior to the occurrence of faults. The development of electromagnetic sensing theory and artificial intelligence algorithms has provided a new method for the monitoring of distribution networks. To address the inverse problem, this work investigates the field distribution around the distribution network, analyzes the characteristics of the power frequency electromagnetic field and partial discharge field. Furthermore, it conducts an analysis of the feasibility of using electromagnetic sensing theory to monitor the operational status of the distribution network. © 2024 IEEE.

关键词： Electric power distribution

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1.2-Tb/s/λ IM/DD optical Interconnects with Stokes Vector Receiver

1.2-Tb/s/λ IM/DD Optical Interconnects with Stokes Vector R...

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2024 Asia communications and Photonics Conference, ACP 2024 and International Conference on Information Photonics and optical communications, IPOC 2024

作者： Fang, Xiansong Li, Yunchen Hu, Weisheng Li, Ke Zhu, Yixiao Yang, Chuanchuan He, Zhixue Zhang, Fan Zhou, Lingjun Zhou, Xian Wang, Lei State Key Laboratory of Advanced Optical Communication System and Networks School of Electronics Peking University Beijing China Pengcheng Laboratory Shenzhen China State Key Laboratory of Advanced Optical Communication System and Networks Shanghai Jiao Tong University Shanghai China Beijing Engineering and Technology Research Center for Convergence Networks and Ubiquitous Services University of Science and Technology Beijing Beijing China

We demonstrate the first 1.2Tb/s/λ line rate IM/DD optical interconnects using ultra-high-order modulation and Stokes vector receiver. This achievement utilizes polarization division multiplexing and 154-GBd PS-PAM20... 详细信息

ISBN: (纸本)9798350379266

关键词： optical interconnects

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