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The Transformation of Normalization Standard of Smith Chart for Microwave Networks With Multiple Impedance Transmission Lines

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IEEE Microwave and Wireless Technology Letters 2025年第4期35卷 384-387页

作者： Yi, Zixuan Hu, Peipei Yang, Xue-Xia Li, Meiling Zeng, Dan Shanghai Institute for Advanced Communication and Data Science Key Laboratory of Specialty Fiber Optics and Optical Access Networks Shanghai University Shanghai200444 China

The Smith chart is a graphical approach for solving impedance matching problems in the microwave circuit design, which provides visualized traces, but it is not applicable to address impedance discontinuities graphically, especially for multiple-impedance transmission lines (TLs) within microwave networks. In this letter, a novel transformation of normalization standard (TNS) method is proposed, which is applied to the Smith chart to solve the aforementioned problem. Then, TNS traces are derived and applied to the classical Smith chart, obtaining an improved Smith chart. In addition, the TNS idea is applied to the microwave circuit design examples. The proposed TNS method provides a convenient visualized way for the design of microwave circuits with multi-impedance TLs. © 2023 IEEE.

关键词： Integrated circuit design

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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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Recticoil for Efficient Compact Inductive Power Transfer

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IEEE Transactions on Power Electronics 2025年第7期40卷 10154-10164页

作者： Yi, Zixuan Qin, Yuanyuan Yang, Xue-Xia Shao, Yaoxia Zeng, Dan Li, Meiling Shanghai University School of Communication and Information Engineering Key Laboratory of Specialty Fiber Optics and Optical Access Networks Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication Shanghai Institute for Advanced Communication and Data Science Shanghai200444 China Hangzhou City University School of Information and Electrical Engineering Hangzhou310015 China

The MHz inductive power transfer (IPT) system has broad application prospects due to its high safety, longer transmission distance, and better tolerance for misalignment. However, the increase in frequency will lead to an increased loss of lumped components, such as inductors and capacitors, in peripheral circuits, thereby reducing efficiency. This is currently the bottleneck problem encountered by MHz IPT. To address this key challenge, researchers have tried to remove the lumped components in the peripheral circuit while ensuring the functions of the IPT system. One successful and beneficial attempt is the self-resonant coil, which replaces traditional lumped resonant capacitors with distributed capacitors formed by coil turn-to-turn capacitance, ensuring compensation for leakage inductance and eliminating reactive power. This innovative integration makes efficiency and integration greatly improved. In this article, the novel coil named Recticoil, on which the rectification function is integrated further, is proposed for efficient compact IPT. Recticoil can directly output dc power without additional compensation and rectification circuits. By analyzing a toroidal coil where two separate conductors generate a voltage differential, and incorporating two diodes, resulting in a dc output. Subsequently, the self-resonant coil replaces the toroidal coil to form Recticoil, and the equivalent circuits of Recticoil are given and analyzed. In addition, the analysis and test method of rectification efficiency is given. The experimental results show that the Recticoil achieves a rectification efficiency as high as 97.25% at 6.78 MHz, outperforming both the bridge rectifier and the Class E rectifier. Additionally, the compact construction of Recticoil eliminates the volume of traditional rectifiers. All of these advantages of Recticoil render it a promising candidate for applications in wearables and miniaturized devices. © 1986-2012 IEEE.

关键词： Equivalent circuits

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Dynamic fabrication method of SNAP microresonators

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Optics Letters 2025年第9期50卷 3042-3045页

作者： Wang, Zijie Crespo-Ballesteros, Manuel Collins, Christopher Yang, Yong Zhang, Qi Zhang, Xiaobei Sumetsky, Michael Aston Institute of Photonics Technology Aston University Aston Triangle BirminghamB47ET United Kingdom Key Laboratory of Specialty Fiber Optics and Optical Access Networks Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication Shanghai Institute for Advanced Communication and Data Science Shanghai University Shanghai200444 China

Surface nanoscale axial photonics (SNAP) technology has demonstrated the record subangstrom fabrication precision of optical microresonators and resonant photonic circuits at the optical fiber surface. However, fabrication errors arising from fluctuations of temperature, inscription parameters, alignment inconsistencies, and other factors did not allow researchers to achieve the subangstrom precision without sophisticated post-processing. Here, we show that the key fabrication method of SNAP structures—CO2 laser beam optical fiber annealing—suffers from significant fiber displacements, which may introduce a few percent fabrication errors. To suppress the effects of misalignment, we develop a dynamic fabrication method employing a translating beam exposure and demonstrate its excellent precision. An effective fiber radius variation of ∼10 nm is introduced with an error of ∼0.1 Å. We suggest that the remaining fabrication errors can be attributed to laser power fluctuations. © 2025 Optica Publishing Group. All rights,

关键词： Optical fiber fabrication

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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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Wav2Lip Bridges communication Gap: Automating Lip Sync and Language Translation for Indian Languages

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IEEE Access 2025年 13卷 72906-72917页

作者： Venkataraghavan, Vaishnavi Sivapatham, Shoba Kar, Asutosh Vellore Institute of Technology School of Electronics Engineering Chennai600127 India Vellore Institute of Technology Centre for Advanced Data Science Chennai600127 India Dr B R Ambedkar National Institute of Technology Electronics and Communication Engineering Punjab Jalandhar144011 India

Translating spoken speech in videos from one language to another is known as audio-visual translation (AVT). This paper describes the implementation of an automated AVT and lip-synced dubbing application. It addresses the difficulty of synchronizing mouth movements with translated speech by building a web application that synthesizes the speaker’s lip movements to match translated audio. Using ASR models, the speech from the source video is converted to text, translated into several languages, and then automatically synthesized into speech in the target language. A lip synchronization model, Wav2Lip, is used to alter the mouth movements in the video to correspond to the target language. We compare our work with two wellknown ASR systems: Wav2vec 2.0 and Google Speech Recognition. Wav2vec 2.0 performs better with the lesser average WER% of 15.38 and is used in our final web application. The performance of the video dubbing component is discussed with the generated speech in Tamil, Telugu, Hindi, and English, and we determine that our generated videos outperform the existing ones. Our proposed AVT application is user-friendly for a wide variety of speakers, utilizing readily available TTS systems instead of training on an individual speaker’s voice. © 2013 IEEE.

关键词： Speech recognition

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RGB-D Rail Surface Defect Inspection Driven by Conditional Diffusion Architecture and Frequency Knowledge

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IEEE Sensors Journal 2025年第10期25卷 18334-18343页

作者： He, Zhihao Li, Gongyang Liu, Zhi Shanghai University School of Communication and Information Engineering Shanghai200444 China Anhui Province Key Laboratory of Machine Vision Detection and Perception Wuhu241000 China Wenzhou Institute of Shanghai University Wenzhou325000 China Shanghai Institute for Advanced Communication and Data Science School of Communication and Information Engineering Shanghai University Key Laboratory of Specialty Fiber Optics and Optical Access Networks Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication Shanghai200444 China

RGB-D rail surface defect inspection (RSDI) is a critical measure for ensuring transportation safety. It improves inspection accuracy by using depth maps, but the issue of poor-quality depth maps in rail defect datasets is often overlooked. Additionally, the similarity between the foreground and the background has always been a persistent challenge in RGB-D RSDI. In this article, we propose a novel network, termed DiffRSDI to overcome these challenges in RGB-D RSDI, which treats RGB-D RSDI as a mask generation task using a conditional diffusion architecture. Specifically, DiffRSDI consists of two key components: a cross-modal cyclic enhancement (CCE) module and a frequency-aware alternate fusion (FAF) module. The CCE module is based on the cyclic enhancement approach and aims to eliminate interference from poor-quality depth maps and aggregate cross-modal features. The FAF module overcomes the similarity between the foreground and the background in the frequency domain and achieves cross-scale fusion in the fused features. Comprehensive experiments conducted on the NEU RSDDS-AUG dataset confirm that our method achieves superior performance in comparison to 14 related methods. © 2001-2012 IEEE.

关键词： Railroad accidents

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In-depth development of temperature insensitive refractive index Fabry-Perot optical sensor 2

In-depth development of temperature insensitive refractive i...

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2nd International Conference on Optical communication and Optical Information Processing, OCOIP 2024

作者： Gao, Yuda Luo, Yanhua Institute of Fiber Optics Key Laboratory of Specialty Fiber Optics and Optical Access Networks Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication Shanghai Institute for Advanced Communication and Data Science Shanghai University Shanghai200444 China

ISBN: (数字)9781510688995

ISBN: (纸本)9781510688988

Sensors based on optical fiber interference structures offer benefits such as high sensitivity, simple fabrication and good compatibility, and are widely used in fields like biological monitoring, chemical engineering, and environmental monitoring. However, these sensors often face unavoidable cross-sensitivity issues between temperature and refractive index. Therefore, developing a new optical fiber refractive index sensor that is insensitive to temperature and has a broad refractive index measurement range remains a significant research issue. In this work, proposing a temperature-insensitive refractive index sensor featuring a two-stage Fabry-Perot (F-P) cavity made from single-mode fiber (SMF), capillary fiber (CF), and no core fiber (NCF) based on the principle of mode interference. The research experimentally investigates the sensor's sensitivity to temperature and refractive index. Results indicate that the sensor's amplitude correlates linearly with the refractive index in both optical and Fourier domains, covering a refractive index range of 1.3164 to 1.4215. In the Fourier domains, sensitivities of - 0.7184/refractive index unit (RIU) and - 0.2672/RIU are recorded at two distinct positions, respectively. A direct relationship between the amplitude and the refractive index is established. Additionally, the proposed sensor is almost insensitive to temperature in both the wavelength and Fourier domains. At the same time, experimental validation using water, ethanol, isopropanol, and glycerin solutions with varying refractive indexes, yielding results that align well with the established refractive index relationship. © 2025 SPIE.

关键词： Fabry-Perot interferometers

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Characteristics of Forward Stimulated Brillouin Scattering Temperature Sensor Based on Single Mode PbS-doped Optical Fiber 4

Characteristics of Forward Stimulated Brillouin Scattering T...

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4th International Computational Imaging Conference, CITA 2024

作者： Chen, Yu Li, Yichun Zhang, Liang Dong, Yanhua Dong, Qianni Wen, Jianxiang Zhu, Mengshi Wei, Heming Pang, Fufei Wang, Tingyun Key Laboratory of Specialty Fiber Optics and Optical Access Networks Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication Shanghai Institute for Advanced Communication and Data Science Shanghai University Shanghai200444 China

ISBN: (纸本)9781510688834

Forward stimulated Brillouin scattering (FSBS) has garnered increasing attention owing to its ability to sense the surrounding environment through photon-phonon interaction between optical waves and guided transverse acoustic resonances. Compared to conventional standard single mode fibers (SSMFs), the utilization of specialty fibers with diverse fiber core/cladding geometries (e.g., thin-diameter fibers, large effective area fibers, few mode fibers, and photonic crystal fibers) offers striking opportunities to enhance the FSBS interaction and diversify its functionality. In this work, temperature sensing characteristics of FSBS in single mode PbS-nanoparticle-doped optical fiber (PbSF) have been experimentally investigated. A piece of home-made single mode PbSF fiber with enlarged refractive index difference between the fiber cladding and PbS nanoparticles doped fiber core is fabricated, exhibiting a mode field diameter of 7.9 μm which hence allows for intensified optical field confinement with respect to conventional SSMFs. Results show that the intensity of high order FSBS resonant peaks of PbSF is greater than that of SSMF by more than ten-fold enhancement. By increasing and decreasing the ambient temperature, it is confirmed that the PbSF-based FSBS sensor exhibits a temperature sensitivity of 78.38 kHz/℃ at the highest 19th order of FSBS acoustic resonance. In our experiments, a minimum temperature resolution of 0.20 ℃ at the 15th order of acoustic resonance was detected. These findings indicate that the utilization of PbSF, instead of SSMF, as the sensing element in FSBS-based sensors would be beneficial to achieve high-performance temperature measurement. © 2025 SPIE.

关键词： Stimulated Brillouin scattering

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A Digital Twin and Consensus Empowered Cooperative Control Framework for Platoon-Based Autonomous Driving

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清华大学学报自然科学版（英文版） 2025年第3期30卷 1096-1111页

作者： Jiayu Cao Supeng Leng Kai Xiong Xiaosha Chen School of Information and Communication Engineering University of Electronic Science and Technology of ChinaChengdu 611731China Shenzhen Institute for Advanced Study University of Electronic Science and Technology of ChinaShenzhen 518110China College of Computer Science and Technology and also with College of Data Science Taiyuan University of TechnologyTaiyuan 030024China

Platoon-based autonomous driving is indispensable for traffic automation,but it confronts substantial constraints in rugged terrains with unreliable links and scarce communication *** paper proposes a novel hierarchical Digital Twin(DT)and consensus empowered cooperative control framework for safe driving in harsh ***,leveraging intra-platoon information exchange,one platoon-level DT is constructed on the leader and multiple vehicle-level DTs are distributed among platoon *** leader first makes critical platoon-driving decisions based on the platoon-level ***,considering the impact of unreliable links on the platoon-level DT accuracy and the consequent risk of unsafe decision-making,a distributed consensus scheme is proposed to negotiate critical decisions *** successful negotiation,vehicles proceed to execute critical decisions,relying on their vehicle-level ***,a Space-Air-Ground-Integrated-Network(SAGIN)enabled information exchange is utilized to update the platoon-level DT for subsequent safe decision-making in scenarios with unreliable links,no roadside units,and obstructed ***,based on this framework,an adaptive platooning scheme is designed to minimize total delay and ensure driving *** results indicate that our proposed scheme improves driving safety by 21.1％and reduces total delay by 24.2％in harsh areas compared with existing approaches.

关键词： platoon autonomous driving distributed consensus digital twin space-air-ground integrated network

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