This paper examines the design and optimization of optical fibers for high-speed data transmission, emphasizing advancements that maximize efficiency in modern communication networks. Optical fibers, core components o...This paper examines the design and optimization of optical fibers for high-speed data transmission, emphasizing advancements that maximize efficiency in modern communication networks. Optical fibers, core components of global communication infrastructure, are capable of transmitting data over long distances with minimal loss through principles like total internal reflection. This study explores single-mode and multi-mode fiber designs, providing an overview of key parameters such as core diameter, refractive index profile, and numerical aperture. Mathematical modeling using Maxwell’s equations plays a central role in optimizing fiber performance, helping engineers mitigate challenges like attenuation and dispersion. The paper also discusses advanced techniques, including dense wavelength division multiplexing (DWDM), which enables terabit-per-second data rates. Case studies in practical applications, such as fiber-to-the-home (FTTH) networks and transoceanic cables, highlight the impact of optimized designs on network performance. Looking forward, innovations in photonic crystal fibers and hollow-core fibers are expected to drive further improvements, enabling ultra-high-speed data transmission. The paper concludes by underscoring the significance of continuous research and development to address challenges in optical fiber technology and support the increasing demands of global communication systems.展开更多
In order to ensure the uninterrupted communication between high-speed train and base station,driving safety and satisfying online experience of passengers,a dual-link switching algorithm based on CNN-WaveNet decision ...In order to ensure the uninterrupted communication between high-speed train and base station,driving safety and satisfying online experience of passengers,a dual-link switching algorithm based on CNN-WaveNet decision parameter multi-step prediction model is proposed to establish a two-hop relay communication system model between the high-speed train and the base station.Firstly,the switching algorithm uses convolution neural network(CNN)to extract the time sequence characteristics of decision parameters.Then,it learns the mapping relationship between feature information and decision parameters based on WaveNet and combining with rolling prediction method to realize multi-step prediction of decision parameters.Finally,dual-antenna communication mode is adopted to realize dual-link communication.The simulation results show that the proposed handover algorithm can improve handover trigger rate and handover success rate.展开更多
A chaotic communication scheme with a fibre ring inserted in the optical ~eedback of the transmitter laser as an additional key is proposed under anticipating synchronization. The numerical results show that the key c...A chaotic communication scheme with a fibre ring inserted in the optical ~eedback of the transmitter laser as an additional key is proposed under anticipating synchronization. The numerical results show that the key can enhance the communication security effectively. It is theoretically safe for the communication scheme to transmit messages with a frequency beyond the relaxation oscllation frequency.展开更多
This study explores the application of single photon detection(SPD)technology in underwater wireless optical communication(UWOC)and analyzes the influence of different modulation modes and error correction coding type...This study explores the application of single photon detection(SPD)technology in underwater wireless optical communication(UWOC)and analyzes the influence of different modulation modes and error correction coding types on communication performance.The study investigates the impact of on-off keying(OOK)and 2-pulse-position modulation(2-PPM)on the bit error rate(BER)in single-channel intensity and polarization multiplexing.Furthermore,it compares the error correction performance of low-density parity check(LDPC)and Reed-Solomon(RS)codes across different error correction coding types.The effects of unscattered photon ratio and depolarization ratio on BER are also verified.Finally,a UWOC system based on SPD is constructed,achieving 14.58 Mbps with polarization OOK multiplexing modulation and 4.37 Mbps with polarization 2-PPM multiplexing modulation using LDPC code error correction.展开更多
Chaotic optical communication has shown large potential as a hardware encryption method in the physical layer.As an important figure of merit,the bit rate–distance product of chaotic optical communication has been co...Chaotic optical communication has shown large potential as a hardware encryption method in the physical layer.As an important figure of merit,the bit rate–distance product of chaotic optical communication has been continually improved to 30 Gb/s×340 km,but it is still far from the requirement for a deployed optical fiber communication system,which is beyond 100 Gb/s×1000 km.A chaotic carrier can be considered as an analog signal and suffers from fiber channel impairments,limiting the transmission distance of high-speed chaotic optical communications.To break the limit,we propose and experimentally demonstrate a pilot-based digital signal processing scheme for coherent chaotic optical communication combined with deep-learning-based chaotic synchronization.Both transmission impairment recovery and chaotic synchronization are realized in the digital domain.The frequency offset of the lasers is accurately estimated and compensated by determining the location of the pilot tone in the frequency domain,and the equalization and phase noise compensation are jointly performed by the least mean square algorithm through the time domain pilot symbols.Using the proposed method,100 Gb∕s chaotically encrypted quadrature phase-shift keying(QPSK)signal over 800 km single-mode fiber(SMF)transmission is experimentally demonstrated.In order to enhance security,40 Gb∕s real-time chaotically encrypted QPSK signal over 800 km SMF transmission is realized by inserting pilot symbols and tone in a field-programmable gate array.This method provides a feasible approach to promote the practical application of chaotic optical communications and guarantees the high security of chaotic encryption.展开更多
The rich structure of transverse spatial modes of structured light has facilitated their extensive applications in quantum information and optical communication.The Laguerre-Gaussian(LG)modes,which carry a well-define...The rich structure of transverse spatial modes of structured light has facilitated their extensive applications in quantum information and optical communication.The Laguerre-Gaussian(LG)modes,which carry a well-defined orbital angular momentum(OAM),consist of a complete orthogonal basis describing the transverse spatial modes of light.The application of OAM in free-space optical communication is restricted due to the experimentally limited OAM numbers and the complex OAM recognition methods.Here,we present a novel method that uses the advanced deep learning technique for LG modes recognition.By discretizing the spatial modes of structured light,we turn the OAM state regression into classification.A proof-of-principle experiment is also performed,showing that our method effectively categorizes OAM states with small training samples and the accuracy exceeds 99%from three-dimensional(3D)to fifteen-dimensional(15D)space.By assigning each category a classical information,we further apply our approach to an image transmission task,achieving a transmission accuracy of 99.58%,which demonstrates the ability to encode large data with low OAM number.This work opens up a new avenue for achieving high-capacity optical communication with low OAM number based on structured light.展开更多
Free-space optical communication(FSO)can achieve fast,secure,and license-free communication without physical cables,providing a cost-effective,energy-efficient,and flexible solution when fiber connection is unavailabl...Free-space optical communication(FSO)can achieve fast,secure,and license-free communication without physical cables,providing a cost-effective,energy-efficient,and flexible solution when fiber connection is unavailable.To achieve FSO on demand,portable FSO devices are essential for flexible and fast deployment,where the key is achieving compact structure and plug-and-play operation.Here,we develop a miniaturized FSO system and realize 9.16 Gbps FSO in a 1 km link,using commercial single-mode-fibercoupled optical transceiver modules without optical amplification.Fully automatic four-stage acquisition,pointing,and tracking systems are developed,which control the tracking error within 3μrad,resulting in an average link loss of 13.7 dB.It is the key for removing optical amplification;hence FSO is achieved with direct use of commercial transceiver modules in a bidirectional way.Each FSO device is within an overall size of 45 cm×40 cm×35 cm,and 9.5 kg weight,with power consumption of∼10 W.The optical link up to 4 km is tested with average loss of 18 dB,limited by the foggy test environment.With better weather conditions and optical amplification,longer FSO can be expected.Such a portable and automatic FSO system will produce massive applications of field-deployable high-speed wireless communication in the future.展开更多
In High-Speed Railways(HSRs),the Train Control and Management System(TCMS)plays a crucial role.However,as the demand for train networks grows,the limitations of traditional wired connections have become apparent.This ...In High-Speed Railways(HSRs),the Train Control and Management System(TCMS)plays a crucial role.However,as the demand for train networks grows,the limitations of traditional wired connections have become apparent.This paper designs and implements a Wireless Train Communication Network(WTCN)to enhance the existing train network infrastructure.To address the challenges that wireless communication technology faces in the unique environment of high-speed rail,this study first analyzes various onboard environments and simulates several typical scenarios in the laboratory.Integrating the specific application scenarios and service characteristics of the high-speed train control network,we conduct measurements and validations of WiFi performance,exploring the specific impacts of different factors on throughput and delay.展开更多
In recent years, there has been a revolution in the way that we transmit information through optical communication systems, allowing for fast and high-capacity data transmission using optical communication systems. Du...In recent years, there has been a revolution in the way that we transmit information through optical communication systems, allowing for fast and high-capacity data transmission using optical communication systems. Due to the growing demand for higher-capacity and faster networks, traditional optical communication systems are reaching their limits due to the increasing demand for faster and higher-capacity networks. The advent of machine learning and deep learning approaches has led to the emergence of powerful tools that can dramatically enhance the performance of optical communication systems with significant efficiency improvements. In this paper, we provide an overview of the role that machine learning (ML) and deep learning can play in enhancing the performance of various aspects of optical communication systems, including modulation techniques, channel modelling, equalization, and system optimization methods. The paper discusses the advantages of these approaches, such as improved spectral efficiency, reduced latency, and improved robustness to impairments in the channel, such as spectrum degradation. Additionally, a discussion is made regarding the potential challenges and limitations associated with using machine learning and deep learning in optical communication systems as well as their potential benefits. The purpose of this paper is to provide insight and highlight the potential of these approaches to improve optical communication in the future.展开更多
This paper proposes a novel modified uni-traveling-carrier photodiode(MUTC-PD)featuring an electric field regulation layer:a p-type doped thin layer inserted behind the PD’s n-doped cliff layer.This electric field re...This paper proposes a novel modified uni-traveling-carrier photodiode(MUTC-PD)featuring an electric field regulation layer:a p-type doped thin layer inserted behind the PD’s n-doped cliff layer.This electric field regulation layer enhances the PD’s performance by not only reducing and smoothing the electric field intensity in the collector layer,allowing photo-generated electrons to transit at peak drift velocity,but also improving the electric field intensity in the depleted absorber layer and optimizing the photo-generated carriers’saturated transit performance.Additionally,the transport characteristics of the peak drift velocity of photogenerated electrons in the device’s collection layer can be used to optimize its parasitic characteristics.The electron’s peak drift velocity compensates for the lost transit time.Thus improving the 3 dB bandwidth of the PD’s photo response.Finally obtains a MUTC-PD with a 3 dB bandwidth of 68 GHz at a responsivity of 0.502 A/W,making it suitable for 100 Gbit/s optical receivers.展开更多
In this paper,a double-effect DNN-based Digital Back-Propagation(DBP)scheme is proposed and studied to achieve the Integrated Communication and Sensing(ICS)ability,which can not only realize nonlinear damage mitigatio...In this paper,a double-effect DNN-based Digital Back-Propagation(DBP)scheme is proposed and studied to achieve the Integrated Communication and Sensing(ICS)ability,which can not only realize nonlinear damage mitigation but also monitor the optical power and dispersion profile over multi-span links.The link status information can be extracted by the characteristics of the learned optical fiber parameters without any other measuring instruments.The efficiency and feasibility of this method have been investigated in different fiber link conditions,including various launch power,transmission distance,and the location and the amount of the abnormal losses.A good monitoring performance can be obtained while the launch optical power is 2 dBm which does not affect the normal operation of the optical communication system and the step size of DBP is 20 km which can provide a better distance resolution.This scheme successfully detects the location of single or multiple optical attenuators in long-distance multi-span fiber links,including different abnormal losses of 2 dB,4 dB,and 6 dB in 360 km and serval combinations of abnormal losses of(1 dB,5 dB),(3 dB,3 dB),(5 dB,1 dB)in 360 km and 760 km.Meanwhile,the transfer relationship of the estimated coefficient values with different step sizes is further investigated to reduce the complexity of the fiber nonlinear damage compensation.These results provide an attractive approach for precisely sensing the optical fiber link status information and making correct strategies timely to ensure optical communication system operations.展开更多
The carrier transport layer with reflection reduction morphology has attracted extensive attention for improving the utilization of light.Herein,we introduced single-layer hollow ZnO hemisphere arrays(ZHAs)behaving li...The carrier transport layer with reflection reduction morphology has attracted extensive attention for improving the utilization of light.Herein,we introduced single-layer hollow ZnO hemisphere arrays(ZHAs)behaving light trapping effect as the electron transport layer in perovskite photodetectors(PDs).The singlelayer hollow ZHAs can not only reduce the reflection,but also widen the angle of the effective incident light and especially transfer the distribution of the optical field from the ZnO/FTO interface to the perovskite active layer confirmed by the 3D finitedifference time-domain simulation.These merits benefit for the generation,transport and separation of carriers,improving the light utilization efficiency.Finally,our optimized FTO/ZHA/CsPbBr3/carbon structure PDs showed high self-powered performance with a linear dynamic range of 120.3 dB,a detectivity of 4.2×10^(12) Jones,rise/fall time of 13/28μs and the f_(−3) dB of up to 28 kHz.Benefiting from the high device performance,the PD was demonstrated to the application in the directional transmission of encrypted files as the signal receiving port with super high accuracy.This work uniquely utilizes the features of high-performance self-powered perovskite PDs in optical communication,paving the path to wide applications of all-inorganic perovskite PDs.展开更多
In the intensity modulation and direct detection （IM/DD） multiple-input multiple-output （MIMO） optical wireless communication systems, a direct-current-biased adaptive modulation scheme is proposed to guarantee th...In the intensity modulation and direct detection （IM/DD） multiple-input multiple-output （MIMO） optical wireless communication systems, a direct-current-biased adaptive modulation scheme is proposed to guarantee the nonnegative property of transmitted signals, and the MIMO channel is converted to a parallel channel by using a singular value decomposition. Besides, a QR decomposition and successive interference cancellation based adaptive modulation scheme is proposed, and the MIMO channel can be simplified to a parallel channel under the bit error ratio （BER） target constraint. The power is optimally allocated to each sub-channel to maximize the data rate. Simulation results show that the proposed adaptive modulation schemes can effectively improve the transmission rate of the systems under the BER target and constant optical power constraints. The proposed adaptive modulation schemes make use of the multiplexing gain of the MIMO techniques, and can further improve the spectrum efficiency of optical wireless systems.展开更多
The possibility of visible red light laser being used as signal light source for Free-Space Optical (FSO) communication is proposed. Based on analysis of transmission in atmospheric channel concerning 650 nm laser bea...The possibility of visible red light laser being used as signal light source for Free-Space Optical (FSO) communication is proposed. Based on analysis of transmission in atmospheric channel concerning 650 nm laser beam, performance of wireless laser communication link utilizing a low power red laser diode was evaluated. The proposed system can achieve a maximum range of 300 m at data rate 100 Mb/s theoretically. An experimental short-range link at data rate 10 Mb/s covering 300 m has been implemented in our university. It is feasible to enhance the system performance such as link range and data rate by increasing transmitting power and decreasing laser beam divergence angle or through other approaches.展开更多
In this article,an omnidirectional dual-polarized antenna with synergetic electromagnetic and aerodynamic properties is propounded for high-speed diversity systems.The propounded antenna comprises a probe-fed cavity f...In this article,an omnidirectional dual-polarized antenna with synergetic electromagnetic and aerodynamic properties is propounded for high-speed diversity systems.The propounded antenna comprises a probe-fed cavity for horizontally polarized radiation and a microstrip-fed slot for vertical polarization.Double-layer metasurfaces are properly designed as artificial magnetic conductor boundaries with direct metal-mountable onboard installation and compact sizes.An attached wedge-shaped block is utilized for windage reduction in hydrodynamics.The propounded antenna is fabricated for design verification,and the experimental results agree well with the simulated ones.For vertical polarization,the operating bandwidth is in the range of 2.37–2.55 GHz,and the realized gain variation in the azimuthal radiation pattern is 3.67 decibels(dB).While an impedance bandwidth in the range of 2.45–2.47 GHz and a gain variation of 3.71 dB are also achieved for horizontal polarization.A port isolation more than 33 dB is obtained in a compact volume of 0.247λ_(0)×0.345λ_(0)×0.074λ_(0),whereλ_(0)represents the wavelength in vacuum at the center frequency,wherein the wedge-shaped block is included.The propounded diversity antenna has electromagnetic and aerodynamic merits,and exhibits an excellent potential for high-speed onboard communication.展开更多
The optical wireless communication (OWC) is afading channel because of the effect of atmosphericattenuation. We introduce a cumulant-based adaptive detection technique to providehigh performance for OWC. The received ...The optical wireless communication (OWC) is afading channel because of the effect of atmosphericattenuation. We introduce a cumulant-based adaptive detection technique to providehigh performance for OWC. The received signalof OWC over strong turbulence channels is assumedto be a mixture of K-distributed fading andGaussian distributed thermal noise. In order tomitigate the fading induced by turbulence, thedecision threshold-updating algorithm based onsecond and higher order cumulants is proposed,which is able to operate in an unknown turbulenceenvironment. The performance of the adaptiveprocessing scheme has been evaluated by meansof Monte Carlo simulations. It is shown that theproposed approach proves valuable for a limitednumber K of memory data.展开更多
The Optical Wireless Communication(OWC)offers the high capacity of optical fiber communication with the flexibility of wireless communication.Since it works in the optical region of the ElectroMagnetic(EM)spectrum,it ...The Optical Wireless Communication(OWC)offers the high capacity of optical fiber communication with the flexibility of wireless communication.Since it works in the optical region of the ElectroMagnetic(EM)spectrum,it guarantees safety and security which are critical in radio and microwave frequency communication.The principal objective of this paper is to analyze the indoor OWC systems on these guaranteed features,and safety and security are jointly denoted by the term green.The high obstacle impermeability of optical signals and their directivity strengthen the security of indoor OWC data transmission.The confidentiality and authenticity of optical wireless data can also be preserved with the Quantum Key Distribution(QKD).This paper provides a technological overview and a review of literature about the OWC system that helps to identify the challenges in the path of a ubiquitous deployment of green wireless communication systems.Significant advancements in the sources and detectors are discussed together with the coding,modulation and multiplexing techniques for making highly robust OWC links.The ubiquitous deployment of green OWC necessitates the development of optical transmitters and receivers,performance enhancement techniques,incorporation of uplink and energy harvesting abilities,and safety and security enhancement techniques.Hence,a special emphasis is placed on these aspects and their challenges towards the green implementation.Furthermore,the paper explores some significant indoor applications based on the OWC that have great impacts on the Next Generation Networks(NGN)and the Internet of Things(IoT).展开更多
The user signal quality as well as the performance of transmission link experiences severe loss due to wireless channel fading and propagation loss in high-speed railway scenario.To improve the quality at the receivin...The user signal quality as well as the performance of transmission link experiences severe loss due to wireless channel fading and propagation loss in high-speed railway scenario.To improve the quality at the receiving end,spatial diversity was realized by means of cooperative communication technology based on the uncorrelated characteristics of the channels.The model of mobile communication system in high-speed railway was set up,and a cooperative scheme based on statistics was proposed.Mathematical analysis and simulation results show that the quality of the received signal and the performance of the transmission link are significantly improved using cooperative communication technology compared to that in non-cooperative communication mode.展开更多
This paper is going to review the state-of-the-art of the high-speed 850/940-nm vertical cavity surface emitting laser（VCSEL）, discussing the structural design, mode control and the related data transmission perform...This paper is going to review the state-of-the-art of the high-speed 850/940-nm vertical cavity surface emitting laser（VCSEL）, discussing the structural design, mode control and the related data transmission performance. InGaAs/AlGaAsmultiple quantum well （MQW） was used to increase the differential gain and photon density in VCSEL. The multiple oxidelayers and oxide-confined aperture were well designed in VCSEL to decrease the parasitic capacitance and generate single mode （SM） VCSEL. The maximal modulation bandwidth of 30 GHz was achieved with well-designed VCSEL structure. At the end of the paper, other applications of the near-infrared VCSELs are discussed.展开更多
With the rapid deployment of Next-Generation Networks(NGN),the research community has initiated discussions on an entirely new suite of optical enabling techniques.To pave the way for the development of future wireles...With the rapid deployment of Next-Generation Networks(NGN),the research community has initiated discussions on an entirely new suite of optical enabling techniques.To pave the way for the development of future wireless networks,this article aims to unify the existing infrared,visible light,and ultraviolet subbands while also exploring the potential of the Petahertz(PHz)band to support extremely bandwidth-thirsfy telepresence style applications.Our focus is on the emerging Petahertz Communication(PetaCom)framework,scenario-dependent propagation channels,modulation schemes,system performance,multiple access techniques,and networking.We conclude with a range of PetaCom challenges and open research issues.展开更多
文摘This paper examines the design and optimization of optical fibers for high-speed data transmission, emphasizing advancements that maximize efficiency in modern communication networks. Optical fibers, core components of global communication infrastructure, are capable of transmitting data over long distances with minimal loss through principles like total internal reflection. This study explores single-mode and multi-mode fiber designs, providing an overview of key parameters such as core diameter, refractive index profile, and numerical aperture. Mathematical modeling using Maxwell’s equations plays a central role in optimizing fiber performance, helping engineers mitigate challenges like attenuation and dispersion. The paper also discusses advanced techniques, including dense wavelength division multiplexing (DWDM), which enables terabit-per-second data rates. Case studies in practical applications, such as fiber-to-the-home (FTTH) networks and transoceanic cables, highlight the impact of optimized designs on network performance. Looking forward, innovations in photonic crystal fibers and hollow-core fibers are expected to drive further improvements, enabling ultra-high-speed data transmission. The paper concludes by underscoring the significance of continuous research and development to address challenges in optical fiber technology and support the increasing demands of global communication systems.
基金supported by National Natural Science Foundation of China(Nos.62161016,61661025)Gansu Provincial Science and Technology Plan(No.20JR10RA273)。
文摘In order to ensure the uninterrupted communication between high-speed train and base station,driving safety and satisfying online experience of passengers,a dual-link switching algorithm based on CNN-WaveNet decision parameter multi-step prediction model is proposed to establish a two-hop relay communication system model between the high-speed train and the base station.Firstly,the switching algorithm uses convolution neural network(CNN)to extract the time sequence characteristics of decision parameters.Then,it learns the mapping relationship between feature information and decision parameters based on WaveNet and combining with rolling prediction method to realize multi-step prediction of decision parameters.Finally,dual-antenna communication mode is adopted to realize dual-link communication.The simulation results show that the proposed handover algorithm can improve handover trigger rate and handover success rate.
基金Project supported by the Key Program of National Natural Science Foundation of China (Grant No.60927007)the National Natural Science Foundation of China (Grant No.60908014)the Shanxi Provincial Science Foundation for Youths,China (Grant No.2010021003-4)
文摘A chaotic communication scheme with a fibre ring inserted in the optical ~eedback of the transmitter laser as an additional key is proposed under anticipating synchronization. The numerical results show that the key can enhance the communication security effectively. It is theoretically safe for the communication scheme to transmit messages with a frequency beyond the relaxation oscllation frequency.
基金supported in part by the National Natural Science Foundation of China(Nos.62071441 and 61701464)in part by the Fundamental Research Funds for the Central Universities(No.202151006).
文摘This study explores the application of single photon detection(SPD)technology in underwater wireless optical communication(UWOC)and analyzes the influence of different modulation modes and error correction coding types on communication performance.The study investigates the impact of on-off keying(OOK)and 2-pulse-position modulation(2-PPM)on the bit error rate(BER)in single-channel intensity and polarization multiplexing.Furthermore,it compares the error correction performance of low-density parity check(LDPC)and Reed-Solomon(RS)codes across different error correction coding types.The effects of unscattered photon ratio and depolarization ratio on BER are also verified.Finally,a UWOC system based on SPD is constructed,achieving 14.58 Mbps with polarization OOK multiplexing modulation and 4.37 Mbps with polarization 2-PPM multiplexing modulation using LDPC code error correction.
基金supported by the National Nature Science Foundation of China (Grant No.62025503).
文摘Chaotic optical communication has shown large potential as a hardware encryption method in the physical layer.As an important figure of merit,the bit rate–distance product of chaotic optical communication has been continually improved to 30 Gb/s×340 km,but it is still far from the requirement for a deployed optical fiber communication system,which is beyond 100 Gb/s×1000 km.A chaotic carrier can be considered as an analog signal and suffers from fiber channel impairments,limiting the transmission distance of high-speed chaotic optical communications.To break the limit,we propose and experimentally demonstrate a pilot-based digital signal processing scheme for coherent chaotic optical communication combined with deep-learning-based chaotic synchronization.Both transmission impairment recovery and chaotic synchronization are realized in the digital domain.The frequency offset of the lasers is accurately estimated and compensated by determining the location of the pilot tone in the frequency domain,and the equalization and phase noise compensation are jointly performed by the least mean square algorithm through the time domain pilot symbols.Using the proposed method,100 Gb∕s chaotically encrypted quadrature phase-shift keying(QPSK)signal over 800 km single-mode fiber(SMF)transmission is experimentally demonstrated.In order to enhance security,40 Gb∕s real-time chaotically encrypted QPSK signal over 800 km SMF transmission is realized by inserting pilot symbols and tone in a field-programmable gate array.This method provides a feasible approach to promote the practical application of chaotic optical communications and guarantees the high security of chaotic encryption.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12204312,12104190,and U21A20436)the Natural Science Foundation of Jiangxi Province,China(Grant Nos.20224BAB211014 and 20232BAB201042)+3 种基金the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20210874)the General Project of Natural Science Research in Colleges and Universities of Jiangsu Province,China(Grant No.20KJB140008)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0301705)the China Postdoctoral Science Foundation(Grant No.2021M702628)。
文摘The rich structure of transverse spatial modes of structured light has facilitated their extensive applications in quantum information and optical communication.The Laguerre-Gaussian(LG)modes,which carry a well-defined orbital angular momentum(OAM),consist of a complete orthogonal basis describing the transverse spatial modes of light.The application of OAM in free-space optical communication is restricted due to the experimentally limited OAM numbers and the complex OAM recognition methods.Here,we present a novel method that uses the advanced deep learning technique for LG modes recognition.By discretizing the spatial modes of structured light,we turn the OAM state regression into classification.A proof-of-principle experiment is also performed,showing that our method effectively categorizes OAM states with small training samples and the accuracy exceeds 99%from three-dimensional(3D)to fifteen-dimensional(15D)space.By assigning each category a classical information,we further apply our approach to an image transmission task,achieving a transmission accuracy of 99.58%,which demonstrates the ability to encode large data with low OAM number.This work opens up a new avenue for achieving high-capacity optical communication with low OAM number based on structured light.
基金supported by the National Key R&D Program of China(Grant No.2019YFA0705000)the Leading-Edge Technology Program of Jiangsu Natural Science Foundation(Grant No.BK20192001)+6 种基金the National Natural Science Foundation of China(Grant Nos.51890861,11690033,and 62293523)the Zhangjiang Laboratory(Grant No.ZJSP21A001)the Key R&D Program of Guangdong Province(Grant No.2018B030329001)the National Postdoctoral Program for Innovative Talents(Grant No.BX2021122)the China Postdoctoral Science Foundation(Grant No.2022M711570)the Fundamental Research Funds for the Central Universities(Grant No.2022300158)the Jiangsu Funding Program for Excellent Postdoctoral Talent.
文摘Free-space optical communication(FSO)can achieve fast,secure,and license-free communication without physical cables,providing a cost-effective,energy-efficient,and flexible solution when fiber connection is unavailable.To achieve FSO on demand,portable FSO devices are essential for flexible and fast deployment,where the key is achieving compact structure and plug-and-play operation.Here,we develop a miniaturized FSO system and realize 9.16 Gbps FSO in a 1 km link,using commercial single-mode-fibercoupled optical transceiver modules without optical amplification.Fully automatic four-stage acquisition,pointing,and tracking systems are developed,which control the tracking error within 3μrad,resulting in an average link loss of 13.7 dB.It is the key for removing optical amplification;hence FSO is achieved with direct use of commercial transceiver modules in a bidirectional way.Each FSO device is within an overall size of 45 cm×40 cm×35 cm,and 9.5 kg weight,with power consumption of∼10 W.The optical link up to 4 km is tested with average loss of 18 dB,limited by the foggy test environment.With better weather conditions and optical amplification,longer FSO can be expected.Such a portable and automatic FSO system will produce massive applications of field-deployable high-speed wireless communication in the future.
基金support from the Beijing Engineering Research Center of High-speed Railway Broadband Mobile Communications(BHRC-2024-1)Beijing Jiaotong University,the National Natural Science Foundation of China(U21A20445).
文摘In High-Speed Railways(HSRs),the Train Control and Management System(TCMS)plays a crucial role.However,as the demand for train networks grows,the limitations of traditional wired connections have become apparent.This paper designs and implements a Wireless Train Communication Network(WTCN)to enhance the existing train network infrastructure.To address the challenges that wireless communication technology faces in the unique environment of high-speed rail,this study first analyzes various onboard environments and simulates several typical scenarios in the laboratory.Integrating the specific application scenarios and service characteristics of the high-speed train control network,we conduct measurements and validations of WiFi performance,exploring the specific impacts of different factors on throughput and delay.
文摘In recent years, there has been a revolution in the way that we transmit information through optical communication systems, allowing for fast and high-capacity data transmission using optical communication systems. Due to the growing demand for higher-capacity and faster networks, traditional optical communication systems are reaching their limits due to the increasing demand for faster and higher-capacity networks. The advent of machine learning and deep learning approaches has led to the emergence of powerful tools that can dramatically enhance the performance of optical communication systems with significant efficiency improvements. In this paper, we provide an overview of the role that machine learning (ML) and deep learning can play in enhancing the performance of various aspects of optical communication systems, including modulation techniques, channel modelling, equalization, and system optimization methods. The paper discusses the advantages of these approaches, such as improved spectral efficiency, reduced latency, and improved robustness to impairments in the channel, such as spectrum degradation. Additionally, a discussion is made regarding the potential challenges and limitations associated with using machine learning and deep learning in optical communication systems as well as their potential benefits. The purpose of this paper is to provide insight and highlight the potential of these approaches to improve optical communication in the future.
文摘This paper proposes a novel modified uni-traveling-carrier photodiode(MUTC-PD)featuring an electric field regulation layer:a p-type doped thin layer inserted behind the PD’s n-doped cliff layer.This electric field regulation layer enhances the PD’s performance by not only reducing and smoothing the electric field intensity in the collector layer,allowing photo-generated electrons to transit at peak drift velocity,but also improving the electric field intensity in the depleted absorber layer and optimizing the photo-generated carriers’saturated transit performance.Additionally,the transport characteristics of the peak drift velocity of photogenerated electrons in the device’s collection layer can be used to optimize its parasitic characteristics.The electron’s peak drift velocity compensates for the lost transit time.Thus improving the 3 dB bandwidth of the PD’s photo response.Finally obtains a MUTC-PD with a 3 dB bandwidth of 68 GHz at a responsivity of 0.502 A/W,making it suitable for 100 Gbit/s optical receivers.
基金supported by the National Key Research and Development Program of China (2019YFB1803905)the National Natural Science Foundation of China (No.62171022)+2 种基金Beijing Natural Science Foundation (4222009)Guangdong Basic and Applied Basic Research Foundation (2021B1515120057)the Scientific and Technological Innovation Foundation of Shunde Graduate School,USTB (No.BK19AF005)。
文摘In this paper,a double-effect DNN-based Digital Back-Propagation(DBP)scheme is proposed and studied to achieve the Integrated Communication and Sensing(ICS)ability,which can not only realize nonlinear damage mitigation but also monitor the optical power and dispersion profile over multi-span links.The link status information can be extracted by the characteristics of the learned optical fiber parameters without any other measuring instruments.The efficiency and feasibility of this method have been investigated in different fiber link conditions,including various launch power,transmission distance,and the location and the amount of the abnormal losses.A good monitoring performance can be obtained while the launch optical power is 2 dBm which does not affect the normal operation of the optical communication system and the step size of DBP is 20 km which can provide a better distance resolution.This scheme successfully detects the location of single or multiple optical attenuators in long-distance multi-span fiber links,including different abnormal losses of 2 dB,4 dB,and 6 dB in 360 km and serval combinations of abnormal losses of(1 dB,5 dB),(3 dB,3 dB),(5 dB,1 dB)in 360 km and 760 km.Meanwhile,the transfer relationship of the estimated coefficient values with different step sizes is further investigated to reduce the complexity of the fiber nonlinear damage compensation.These results provide an attractive approach for precisely sensing the optical fiber link status information and making correct strategies timely to ensure optical communication system operations.
基金the National Natural Science Foundation of China(Nos.51972101,11874143)the Natural Science Foundation of Hubei Province(No.2019CFB508)the Application Fundamental Research Project of Wuhan Science and Technology Bureau(No.2019010701011396).
文摘The carrier transport layer with reflection reduction morphology has attracted extensive attention for improving the utilization of light.Herein,we introduced single-layer hollow ZnO hemisphere arrays(ZHAs)behaving light trapping effect as the electron transport layer in perovskite photodetectors(PDs).The singlelayer hollow ZHAs can not only reduce the reflection,but also widen the angle of the effective incident light and especially transfer the distribution of the optical field from the ZnO/FTO interface to the perovskite active layer confirmed by the 3D finitedifference time-domain simulation.These merits benefit for the generation,transport and separation of carriers,improving the light utilization efficiency.Finally,our optimized FTO/ZHA/CsPbBr3/carbon structure PDs showed high self-powered performance with a linear dynamic range of 120.3 dB,a detectivity of 4.2×10^(12) Jones,rise/fall time of 13/28μs and the f_(−3) dB of up to 28 kHz.Benefiting from the high device performance,the PD was demonstrated to the application in the directional transmission of encrypted files as the signal receiving port with super high accuracy.This work uniquely utilizes the features of high-performance self-powered perovskite PDs in optical communication,paving the path to wide applications of all-inorganic perovskite PDs.
基金The National High Technology Research and Development Program of China(863 Program)(No.2013AA013601)the National Science and Technology M ajor Project of China(No.2015ZX03004009)
文摘In the intensity modulation and direct detection （IM/DD） multiple-input multiple-output （MIMO） optical wireless communication systems, a direct-current-biased adaptive modulation scheme is proposed to guarantee the nonnegative property of transmitted signals, and the MIMO channel is converted to a parallel channel by using a singular value decomposition. Besides, a QR decomposition and successive interference cancellation based adaptive modulation scheme is proposed, and the MIMO channel can be simplified to a parallel channel under the bit error ratio （BER） target constraint. The power is optimally allocated to each sub-channel to maximize the data rate. Simulation results show that the proposed adaptive modulation schemes can effectively improve the transmission rate of the systems under the BER target and constant optical power constraints. The proposed adaptive modulation schemes make use of the multiplexing gain of the MIMO techniques, and can further improve the spectrum efficiency of optical wireless systems.
文摘The possibility of visible red light laser being used as signal light source for Free-Space Optical (FSO) communication is proposed. Based on analysis of transmission in atmospheric channel concerning 650 nm laser beam, performance of wireless laser communication link utilizing a low power red laser diode was evaluated. The proposed system can achieve a maximum range of 300 m at data rate 100 Mb/s theoretically. An experimental short-range link at data rate 10 Mb/s covering 300 m has been implemented in our university. It is feasible to enhance the system performance such as link range and data rate by increasing transmitting power and decreasing laser beam divergence angle or through other approaches.
基金support from the Natural Science Foundation of Beijing Manipulate (4182029)the Youth Top Program of Beijing Outstanding Talent Funding Projectthe National Key Research and Development Program of China (2018YFB1801603)
文摘In this article,an omnidirectional dual-polarized antenna with synergetic electromagnetic and aerodynamic properties is propounded for high-speed diversity systems.The propounded antenna comprises a probe-fed cavity for horizontally polarized radiation and a microstrip-fed slot for vertical polarization.Double-layer metasurfaces are properly designed as artificial magnetic conductor boundaries with direct metal-mountable onboard installation and compact sizes.An attached wedge-shaped block is utilized for windage reduction in hydrodynamics.The propounded antenna is fabricated for design verification,and the experimental results agree well with the simulated ones.For vertical polarization,the operating bandwidth is in the range of 2.37–2.55 GHz,and the realized gain variation in the azimuthal radiation pattern is 3.67 decibels(dB).While an impedance bandwidth in the range of 2.45–2.47 GHz and a gain variation of 3.71 dB are also achieved for horizontal polarization.A port isolation more than 33 dB is obtained in a compact volume of 0.247λ_(0)×0.345λ_(0)×0.074λ_(0),whereλ_(0)represents the wavelength in vacuum at the center frequency,wherein the wedge-shaped block is included.The propounded diversity antenna has electromagnetic and aerodynamic merits,and exhibits an excellent potential for high-speed onboard communication.
文摘The optical wireless communication (OWC) is afading channel because of the effect of atmosphericattenuation. We introduce a cumulant-based adaptive detection technique to providehigh performance for OWC. The received signalof OWC over strong turbulence channels is assumedto be a mixture of K-distributed fading andGaussian distributed thermal noise. In order tomitigate the fading induced by turbulence, thedecision threshold-updating algorithm based onsecond and higher order cumulants is proposed,which is able to operate in an unknown turbulenceenvironment. The performance of the adaptiveprocessing scheme has been evaluated by meansof Monte Carlo simulations. It is shown that theproposed approach proves valuable for a limitednumber K of memory data.
基金This publication is an outcome of the R&D work undertaken project under the Visvesvaraya PhD Scheme(Grant No.Ph.D-MLA/4(16))of Ministry of Electronics&Information Technology,Government of India,being implemented by Digital India Corporation.
文摘The Optical Wireless Communication(OWC)offers the high capacity of optical fiber communication with the flexibility of wireless communication.Since it works in the optical region of the ElectroMagnetic(EM)spectrum,it guarantees safety and security which are critical in radio and microwave frequency communication.The principal objective of this paper is to analyze the indoor OWC systems on these guaranteed features,and safety and security are jointly denoted by the term green.The high obstacle impermeability of optical signals and their directivity strengthen the security of indoor OWC data transmission.The confidentiality and authenticity of optical wireless data can also be preserved with the Quantum Key Distribution(QKD).This paper provides a technological overview and a review of literature about the OWC system that helps to identify the challenges in the path of a ubiquitous deployment of green wireless communication systems.Significant advancements in the sources and detectors are discussed together with the coding,modulation and multiplexing techniques for making highly robust OWC links.The ubiquitous deployment of green OWC necessitates the development of optical transmitters and receivers,performance enhancement techniques,incorporation of uplink and energy harvesting abilities,and safety and security enhancement techniques.Hence,a special emphasis is placed on these aspects and their challenges towards the green implementation.Furthermore,the paper explores some significant indoor applications based on the OWC that have great impacts on the Next Generation Networks(NGN)and the Internet of Things(IoT).
基金Project of Science and Technology Research and Development Plan of China Railway Corporation(No.2013G010-D)Foundation of a Hundred Youth Talent Training Program of Lanzhou Jiaotong University
文摘The user signal quality as well as the performance of transmission link experiences severe loss due to wireless channel fading and propagation loss in high-speed railway scenario.To improve the quality at the receiving end,spatial diversity was realized by means of cooperative communication technology based on the uncorrelated characteristics of the channels.The model of mobile communication system in high-speed railway was set up,and a cooperative scheme based on statistics was proposed.Mathematical analysis and simulation results show that the quality of the received signal and the performance of the transmission link are significantly improved using cooperative communication technology compared to that in non-cooperative communication mode.
文摘This paper is going to review the state-of-the-art of the high-speed 850/940-nm vertical cavity surface emitting laser（VCSEL）, discussing the structural design, mode control and the related data transmission performance. InGaAs/AlGaAsmultiple quantum well （MQW） was used to increase the differential gain and photon density in VCSEL. The multiple oxidelayers and oxide-confined aperture were well designed in VCSEL to decrease the parasitic capacitance and generate single mode （SM） VCSEL. The maximal modulation bandwidth of 30 GHz was achieved with well-designed VCSEL structure. At the end of the paper, other applications of the near-infrared VCSELs are discussed.
基金supported by the Key Program of the National Natural Science Foundation of China(No.61631018),Key Research Program of Frontier Sciences of CAS(No.QYZDY-SSW-JSC003)Strategic Priority Research Program of CAS(No.XDA22000000).L.Hanzo would like to acknowledge the financial support of the Engineering and Physical Sciences Research Council projects EP/P034284/1 and EP/P003990/1(COALESCE)as well as of the European Research Council’s Advanced Fellow Grant QuantCom(Grant No.789028).
文摘With the rapid deployment of Next-Generation Networks(NGN),the research community has initiated discussions on an entirely new suite of optical enabling techniques.To pave the way for the development of future wireless networks,this article aims to unify the existing infrared,visible light,and ultraviolet subbands while also exploring the potential of the Petahertz(PHz)band to support extremely bandwidth-thirsfy telepresence style applications.Our focus is on the emerging Petahertz Communication(PetaCom)framework,scenario-dependent propagation channels,modulation schemes,system performance,multiple access techniques,and networking.We conclude with a range of PetaCom challenges and open research issues.
