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Simultaneous transmission of time-frequency and data with co-amplification over urban fiber links

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Chinese optics Letters 2024年第1期22卷 28-33页

作者：操前童周刘雷王家亮应康庞拂飞桂有珍 key laboratory of specialty Fiber optics and optical access networks School of Communication and Information EngineeringShanghai UniversityShanghai 200444China key laboratory for Quantum optics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China key laboratory of Space Laser Communication and Detection Technology Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

We demonstrate a simultaneous transmission of time-frequency and data over a 160-km urban business network in Shanghai.The signals are transmitted through a cascaded optical link consisting of 48 km and 32 km,which are connected by an optical relay.The metrological signals are inserted into the communication network using dense wavelength division multiplexing.The influence of the interference between different signals has been discussed.The experimental results demonstrate that the radio frequency(RF)instability can reach 2.1×10^(-14)at 1 s and 2.3×10^(-17)at 10,000 s,and the time interval transfer of one pulse per second(1 PPS)signal with less than 10 ps at 1 s is obtained.This work paves the way for the widespread dissemination of ultra-stable time and frequency signals over the communication networks.

关键词： simultaneous transmission radio frequency transfer communication network wavelength multiplexing

A wideband,high-resolution vector spectrum analyzer for integrated photonics

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Light(Science & Applications) 2024年第4期13卷 760-771页

作者： Yi-Han Luo Baoqi Shi Wei Sun Ruiyang Chen Sanli Huang Zhongkai Wang Jinbao Long Chen Shen Zhichao Ye Hairun Guo Junqiu Liu International Quantum Academy 518048 ShenzhenChina. Shenzhen Institute for Quantum Science and Engineering Southern University of Science and Technology518055 ShenzhenChina. Department of optics and optical Engineering University of Science and Technology of China230026 HefeiChina. Hefei National laboratory University of Science and Technology of China230088 HefeiChina. Qaleido Photonics 518048 ShenzhenChina. key laboratory of specialty Fiber optics and optical access networks Shanghai University200444 ShanghaiChina

The analysis of optical spectra—emission or absorption—has been arguably the most powerful approach for discovering and understanding matter.The invention and development of many kinds of spectrometers have equipped us with versatile yet ultra-sensitive diagnostic tools for trace gas detection,isotope analysis,and resolving hyperfine structures of atoms and molecules.With proliferating data and information,urgent and demanding requirements have been placed today on spectrum analysis with ever-increasing spectral bandwidth and frequency resolution.These requirements are especially stringent for broadband laser sources that carry massive information and for dispersive devices used in information processing systems.In addition,spectrum analyzers are expected to probe the device’s phase response where extra information is encoded.Here we demonstrate a novel vector spectrum analyzer(VSA)that is capable of characterizing passive devices and active laser sources in one setup.Such a dual-mode VSA can measure loss,phase response,and dispersion properties of passive devices.It also can coherently map a broadband laser spectrum into the RF domain.The VSA features a bandwidth of 55.1 THz(1260–1640 nm),a frequency resolution of 471 kHz,and a dynamic range of 56 dB.Meanwhile,our fiber-based VSA is compact and robust.It requires neither high-speed modulators and photodetectors nor any active feedback control.Finally,we employ our VSA for applications including characterization of integrated dispersive waveguides,mapping frequency comb spectra,and coherent light detection and ranging(LiDAR).Our VSA presents an innovative approach for device analysis and laser spectroscopy,and can play a critical role in future photonic systems and applications for sensing,communication,imaging,and quantum information processing.

关键词： spectrum resolution coherent

Optimizing optical Fiber Faults Detection:A Comparative Analysis of Advanced Machine Learning Approaches

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Computers, Materials & Continua 2024年第5期79卷 2697-2721页

作者： Kamlesh Kumar Soothar Yuanxiang Chen Arif Hussain Magsi Cong Hu Hussain Shah School of Electronics Engineering Beijing University of Posts and TelecommunicationsBeijing100876China State key laboratory of Integrated Services networks Xidian UniversityXi’an710071China State key laboratory ofNetworking and Switching Technology Beijing University of Posts and TelecommunicationsBeijing100876China

Efficient optical network management poses significant importance in backhaul and access network communicationfor preventing service disruptions and ensuring Quality of Service(QoS)satisfaction.The emerging faultsin optical networks introduce challenges that can jeopardize the network with a variety of faults.The existingliterature witnessed various partial or inadequate solutions.On the other hand,Machine Learning(ML)hasrevolutionized as a promising technique for fault detection and prevention.Unlike traditional fault managementsystems,this research has three-fold contributions.First,this research leverages the ML and Deep Learning(DL)multi-classification system and evaluates their accuracy in detecting six distinct fault types,including fiber cut,fibereavesdropping,splicing,bad connector,bending,and PC connector.Secondly,this paper assesses the classificationdelay of each classification algorithm.Finally,this work proposes a fiber optics fault prevention algorithm thatdetermines to mitigate the faults accordingly.This work utilized a publicly available fiber optics dataset namedOTDR_Data and applied different ML classifiers,such as Gaussian Naive Bayes(GNB),Logistic Regression(LR),Support Vector Machine(SVM),K-Nearest Neighbor(KNN),Random Forest(RF),and Decision Tree(DT).Moreover,Ensemble Learning(EL)techniques are applied to evaluate the accuracy of various classifiers.In addition,this work evaluated the performance of DL-based Convolutional Neural Network and Long-Short Term Memory(CNN-LSTM)hybrid classifier.The findings reveal that the CNN-LSTM hybrid technique achieved the highestaccuracy of 99%with a delay of 360 s.On the other hand,EL techniques improved the accuracy in detecting fiberoptic faults.Thus,this research comprehensively assesses accuracy and delay metrics for various classifiers andproposes the most efficient attack detection system in fiber optics.

关键词： Fiber optics fault detection multiclassification machine learning ensemble learning

Monitoring and identifying pendant droplets in microbottle resonators

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Photonics Research 2022年第3期10卷 662-667页

作者： Zijie Wang Xiaobei Zhang Qi Zhang Yiqi Chen Yong Yang Yang Yu Yang Wang Yanhua Dong Yi Huang Tingyun Wang key laboratory of specialty Fiber optics and optical access networks Joint International Research Laboratory of Specialty Fiber Optics and Advanced CommunicationShanghai Institute for Advanced Communication and Data ScienceShanghai UniversityShanghai 200444China

Optofluidic resonators are capable of characterizing various fluidic media.Here,we propose an optofluidic microbottle resonator(OFMBR)that is applied to generate pendant droplets,whose maximum mass is related to the liquid surface tension.Mass and type of droplets forming along the OFMBR stem can be monitored in real time by spectrum variation.As a pendant droplet grows,increased droplet gravity introduces a decreased coupling gap and compressive force between the tapered fiber and OFMBR,leading to a resonance wavelength shift.The operation mechanism of the proposed sensors is validated by theoretical simulation and experimental results.From the experimental spectra,a liquid mass sensor with maximum sensitivity of−3.34pm/mg is obtained,and distilled water and alcohol can be identified.This scheme provides a new thread for droplet generation as well as fluidic properties characterization.

关键词： mechanism coupling alcohol

High signal-to-noise ratio fiber laser at 1596 nm based on a Bi/Er/La co-doped silica fiber

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Chinese optics Letters 2022年第5期20卷 19-23页

作者：杨晶文建湘吴娇万英曾龙别陈伟庞拂飞张小贝王廷云 laboratory of specialty Fiber optics and optical access networks School of Communication and Information EngineeringShanghai UniversityShanghai 200444China

We fabricate a high-performance Bi/Er/La co-doped silica fiber with a fluorescence intensity of-33.8 dBm and a gain coefficient of 1.9 dB/m.With the utilization of the fiber as a gain medium,a linear-cavity fiber laser has been constructed,which exhibits a signal-to-noise ratio of 74.9 dB at 1596 nm.It has been demonstrated that the fiber laser has a maximum output power of 107.4 mW,a slope efficiency of up to 17.0%,and a linewidth of less than 0.02 nm.Moreover,an all-fiber single-stage optical amplifier is built up for laser amplification,by which the amplified laser power is up to 410.0 mW with pump efficiency of 33.8%.The results indicate that the laser is capable of high signal-to-noise ratio and narrow linewidth,with potential applications for optical fiber sensing,biomedicine,precision measurement,and the pump source of the mid-infrared fiber lasers.

关键词： Bi/Er/La co-doped silica fiber high signal-to-noise ratio laser narrow linewidth

Indoor Human Fall Detection Algorithm Based on Wireless Sensing

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Tsinghua Science and Technology 2022年第6期27卷 1002-1015页

作者： Chao Wang Lin Tang Meng Zhou Yinfan Ding Xueyong Zhuang Jie Wu key laboratory of specialty Fiber optics and optical access networks Joint International Research Laboratory of Specialty Fiber Optics and Advanced CommunicationShanghai UniversityShanghai 200444China Department of Computer and Information Sciences Temple UniversityPhiladelphiaPA 19122-6096USA

As the main health threat to the elderly living alone and performing indoor activities,falls have attracted great attention from institutions and society.Currently,fall detection systems are mainly based on wear sensors,environmental sensors,and computer vision,which need to be worn or require complex equipment construction.However,they have limitations and will interfere with the daily life of the elderly.On the basis of the indoor propagation theory of wireless signals,this paper proposes a conceptual verification module using Wi-Fi signals to identify human fall behavior.The module can detect falls without invading privacy and affecting human comfort and has the advantages of noninvasive,robustness,universality,and low price.The module combines digital signal processing technology and machine learning technology.This paper analyzes and processes the channel state information(CSI)data of wireless signals,and the local outlier factor algorithm is used to find the abnormal CSI sequence.The support vector machine and extreme gradient boosting algorithms are used for classification,recognition,and comparative research.Experimental results show that the average accuracy of fall detection based on wireless sensing is more than 90%.This work has important social significance in ensuring the safety of the elderly.

关键词： wireless signal channel status information fall detection wireless sensing

High-power fiber laser with real-time mode switchability

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Chinese optics Letters 2022年第2期20卷 73-79页

作者：吴函烁徐江韬黄良金曾祥龙周朴 College of Advanced Interdisciplinary Studies National University of Defense TechnologyChangsha 410073China key laboratory of specialty Fiber optics and optical access networks Shanghai UniversityShanghai 200444China

A hundred-watt-level spatial mode switchable all-fiber laser is demonstrated based on a master oscillator power amplifier scheme.The performance of the amplifier with two seed lasers,i.e.,with the acoustically induced fiber grating (AIFG) mode converter inside and outside the seed laser cavity,is investigated.Real-time mode switching with millisecond scale switching time between the LP;and LP;modes while operating in full power (>100 W) is realized through an AIFG driven by radio frequency modulation.This work could provide a good reference for realizing high-power agile mode switchable fiber lasers for practical applications.

关键词： acoustically induced fiber grating high power fiber amplifier mode switching

On-chip metamaterial-enabled high-order mode-division multiplexing

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Advanced Photonics 2023年第5期5卷 106-113页

作者： Yu He Xingfeng Li Yong Zhang Shaohua An Hongwei Wang Zhen Wang Haoshuo Chen Yetian Huang Hanzi Huang Nicolas KFontaine Roland Ryf Yuhan Du Lu Sun Xingchen Ji Xuhan Guo Yingxiong Song Qianwu Zhang Yikai Su Shanghai Jiao Tong University Department of Electronic EngineeringState Key Laboratory of Advanced Optical Communication Systems and NetworksShanghaiChina Nokia Bell Labs Murray HillNew JerseyUnited States Shanghai University Key Laboratory of Specialty Fiber Optics and Optical Access NetworksJoint International Research Laboratory of Specialty Fiber Optics and Advanced CommunicationShanghaiChina Shanghai Jiao Tong University School of Electronic Information and Electrical EngineeringJohn Hopcroft Center for Computer ScienceShanghaiChina

Mode-division multiplexing(MDM)technology enables high-bandwidth data transmission using orthogonal waveguide modes to construct parallel data streams.However,few demonstrations have been realized for generating and supporting high-order modes,mainly due to the intrinsic large material groupvelocity dispersion(GVD),which make it challenging to selectively couple different-order spatial modes.We show the feasibility of on-chip GVD engineering by introducing a gradient-index metamaterial structure,which enables a robust and fully scalable MDM process.We demonstrate a record-high-order MDM device that supports TE_(0)–TE_(15)modes simultaneously.40-GBaud 16-ary quadrature amplitude modulation signals encoded on 16 mode channels contribute to a 2.162 Tbit∕s net data rate,which is the highest data rate ever reported for an on-chip single-wavelength transmission.Our method can effectively expand the number of channels provided by MDM technology and promote the emerging research fields with great demand for parallelism,such as high-capacity optical interconnects,high-dimensional quantum communications,and large-scale neural networks.

关键词： integrated photonics metamaterial mode-division multiplexing subwavelength grating

Two-Dimensional DOA Estimation Using One-Dimensional Search for Spherical Arrays

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Chinese Journal of Electronics 2019年第6期28卷 1259-1264页

作者： HUANG Qinghua FENG Jiajun FANG Yong key laboratory of specialty Fiber optics and optical access networks Shanghai University

A Reduced-dimensional spherical harmonics MUSIC(RD-SHMUSIC) is proposed to solve the problem of high computational complexity of Multiple signal classification(MUSIC) algorithm for Twodimensional(2-D) Direction of arrival(DOA) estimation.The proposed algorithm first expresses the spherical harmonic steering vector as a linear weight of a uniform phase vectors. Via the Lagrange multiplier method, we can get a new search function to estimate elevations. At second step, the algorithm expresses the steering vector in another form, a linear weight of a vector which is constructed by associated Legendre functions. A search function to estimate azimuths can also be obtained.The proposed method only needs One dimensional(1-D) angle search, which means it has a large reduction of computational complexity compared to the traditional Spherical harmonics MUSIC(SHMUSIC). The simulation results show that the accuracy of the proposed method is better than Two-stage decoupled approach(TSDA)algorithm, and has close performance to that of SHMUSIC.

关键词： Direction of arrival estimation Spherical arrays Reduced-dimensional spherical harmonics MUSIC Computational complexity