Among physical layer encryption schemes,the quantum noise stream cipher(QNSC)has garnered significant attention due to its compatibility with high-speed commercial fiber-optic communication systems.After careful analy...Among physical layer encryption schemes,the quantum noise stream cipher(QNSC)has garnered significant attention due to its compatibility with high-speed commercial fiber-optic communication systems.After careful analysis of the encryption scheme,we reveal that QNSC transmission systems exhibit a security vulnerability in their encoding scheme.This vulnerability limits quantum noise to alerting high-order information bits in plaintext-dependent regions,creating structured ciphertext concealment.Numerical simulation and experimental verification both indicate that an eavesdropper can use quantization-attack to crack this vulnerability.Existing security assessment methods will overestimate the system's security under quantization-attack.In addition,system security demonstrates a strong linear dependence on the plaintext modulation format,rather than the ciphertext modulation format as is widely presumed.To further enhance system security,the probability distribution is further introduced into the encoding process of ciphertext.The experiment results show that we not only achieved random concealment of ciphertext by quantum noise but also enhanced the eavesdropper's symbol error rate by~86%and maximally expanded the key space of the QAM-QNSC system by 2^(27.2).展开更多
The integration of high-speed optical communication and distributed sensing could bring intelligent functionalities to ubiquitous optical fibre networks,such as urban structure imaging,ocean seismic detection,and safe...The integration of high-speed optical communication and distributed sensing could bring intelligent functionalities to ubiquitous optical fibre networks,such as urban structure imaging,ocean seismic detection,and safety monitoring of underground embedded pipelines.This work demonstrates a scheme of integrated sensing and communication in an optical fibre(ISAC-OF)using the same wavelength channel for simultaneous data transmission and distributed vibration sensing.The scheme not only extends the intelligent functionality for optical fibre communication system,but also improves its transmission performance.A periodic linear frequency modulation(LFM)light is generated to act as the optical carrier and sensing probe in PAM4 signal transmission and phase-sensitive optical time-domain reflectometry(Φ-OTDR),respectively.After a 24.5 km fibre transmission,the forward PAM4 signal and the carriercorrespondence Rayleigh backscattering signal are detected and demodulated.Experimental results show that the integrated solution achieves better transmission performance(~1.3 dB improvement)and a larger launching power(7 dB enhancement)at a 56 Gbit/s bit rate compared to a conventional PAM4 signal transmission.Meanwhile,a 4m spatial resolution,4.32-nε/√Hz strain resolution,and over 21 kHz frequency response for the vibration sensing are obtained.The proposed solution offers a new path to further explore the potential of existing or future fibre-optic networks by the convergence of data transmission and status sensing.In addition,such a scheme of using shared spectrum in communication and distributed optical fibre sensing may be used to measure non-linear parameters in coherent optical communications,offering possible benefits for data transmission.展开更多
For joint modulation format identification(MFI)and optical signal-to-noise ratio(OSNR)monitoring,a simple and intelligent optical communication performance monitoring method is proposed,and the feasibility is demonstr...For joint modulation format identification(MFI)and optical signal-to-noise ratio(OSNR)monitoring,a simple and intelligent optical communication performance monitoring method is proposed,and the feasibility is demonstrated by digital coherent optical communication experiments.The experiment results show that for all modulation formats,including 28 GBaud polarization division multiplexing(PDM)QPSK/8-QAM/16-QAM/64-QAM,100%MFI accuracies are achieved even at OSNR values lower than the corresponding theoretical 20%forward error correction limit,as well as the high accuracies for OSNR monitoring.Furthermore,the proposed scheme has a reasonable monitoring level when chromatic dispersion and fiber nonlinear effects are varied.展开更多
We propose the configuration of signal multiplexing with four polarization states and investigate its transmission performance over single-mode fiber links.Using coherent detection and digital signal processing,a demo...We propose the configuration of signal multiplexing with four polarization states and investigate its transmission performance over single-mode fiber links.Using coherent detection and digital signal processing,a demodulation scheme for four-polarization-multiplexed(4PM)system is presented.We discuss the impact of crosstalk from polarization mode dispersion and polarization beam splitter misalignment on the proposed 4PM system.Furthermore,the transmission distance could be doubled to*50 km by employing feedback decision equalizers.展开更多
A flexible polarization demultiplexing method based on an adaptive Kalman filter（AKF） is proposed in which the process noise covariance has been estimated adaptively. The proposed method may significantly improve th...A flexible polarization demultiplexing method based on an adaptive Kalman filter（AKF） is proposed in which the process noise covariance has been estimated adaptively. The proposed method may significantly improve the adaptive capability of an extended Kalman filter（EKF） by adaptively estimating the unknown process noise covariance. Compared to the conventional EKF, the proposed method can avoid the tedious and time consuming parameter-by-parameter tuning operations. The effectiveness of this method is confirmed experimentally in 128 Gb/s 16 QAM polarization-division-multiplexing（PDM） coherent optical transmission systems. The results illustrate that our proposed AKF has a better tracking accuracy and a faster convergence（about 4 times quicker）compared to a conventional algorithm with optimal process noise covariance.展开更多
基金National Natural Science Foundation of China(62431024,62575248,U22A2089)Key Technology Research and Development Program of Shandong Province(2023CXPT100)Outstanding Young Scientist Fund of Sichuan Provincial Natural Science Foundation(2025NSFJQ0052)。
文摘Among physical layer encryption schemes,the quantum noise stream cipher(QNSC)has garnered significant attention due to its compatibility with high-speed commercial fiber-optic communication systems.After careful analysis of the encryption scheme,we reveal that QNSC transmission systems exhibit a security vulnerability in their encoding scheme.This vulnerability limits quantum noise to alerting high-order information bits in plaintext-dependent regions,creating structured ciphertext concealment.Numerical simulation and experimental verification both indicate that an eavesdropper can use quantization-attack to crack this vulnerability.Existing security assessment methods will overestimate the system's security under quantization-attack.In addition,system security demonstrates a strong linear dependence on the plaintext modulation format,rather than the ciphertext modulation format as is widely presumed.To further enhance system security,the probability distribution is further introduced into the encoding process of ciphertext.The experiment results show that we not only achieved random concealment of ciphertext by quantum noise but also enhanced the eavesdropper's symbol error rate by~86%and maximally expanded the key space of the QAM-QNSC system by 2^(27.2).
基金supported by the National Key Research and Development Program of China(2019YFB1803500)the National Natural Science Foundation of China(NSFC)(61735015,61860206006,62205275,62005228).
文摘The integration of high-speed optical communication and distributed sensing could bring intelligent functionalities to ubiquitous optical fibre networks,such as urban structure imaging,ocean seismic detection,and safety monitoring of underground embedded pipelines.This work demonstrates a scheme of integrated sensing and communication in an optical fibre(ISAC-OF)using the same wavelength channel for simultaneous data transmission and distributed vibration sensing.The scheme not only extends the intelligent functionality for optical fibre communication system,but also improves its transmission performance.A periodic linear frequency modulation(LFM)light is generated to act as the optical carrier and sensing probe in PAM4 signal transmission and phase-sensitive optical time-domain reflectometry(Φ-OTDR),respectively.After a 24.5 km fibre transmission,the forward PAM4 signal and the carriercorrespondence Rayleigh backscattering signal are detected and demodulated.Experimental results show that the integrated solution achieves better transmission performance(~1.3 dB improvement)and a larger launching power(7 dB enhancement)at a 56 Gbit/s bit rate compared to a conventional PAM4 signal transmission.Meanwhile,a 4m spatial resolution,4.32-nε/√Hz strain resolution,and over 21 kHz frequency response for the vibration sensing are obtained.The proposed solution offers a new path to further explore the potential of existing or future fibre-optic networks by the convergence of data transmission and status sensing.In addition,such a scheme of using shared spectrum in communication and distributed optical fibre sensing may be used to measure non-linear parameters in coherent optical communications,offering possible benefits for data transmission.
基金This work was supported by the National Key Research and Development Program of China(No.2021YFB2206303)Key Research and Development Plan of Shandong Province(No.2023CXPT100)+1 种基金Sichuan Science Fund for Distinguished Young Scholars(No.2023NSFSC1969)National Student Research Training Program of China(No.20230613037).
文摘For joint modulation format identification(MFI)and optical signal-to-noise ratio(OSNR)monitoring,a simple and intelligent optical communication performance monitoring method is proposed,and the feasibility is demonstrated by digital coherent optical communication experiments.The experiment results show that for all modulation formats,including 28 GBaud polarization division multiplexing(PDM)QPSK/8-QAM/16-QAM/64-QAM,100%MFI accuracies are achieved even at OSNR values lower than the corresponding theoretical 20%forward error correction limit,as well as the high accuracies for OSNR monitoring.Furthermore,the proposed scheme has a reasonable monitoring level when chromatic dispersion and fiber nonlinear effects are varied.
基金supported by the National Basic Research Program of China(‘‘973’’Program)(2012CB315704)the National Natural Science Foundation of China(61275068,61111140390)
文摘We propose the configuration of signal multiplexing with four polarization states and investigate its transmission performance over single-mode fiber links.Using coherent detection and digital signal processing,a demodulation scheme for four-polarization-multiplexed(4PM)system is presented.We discuss the impact of crosstalk from polarization mode dispersion and polarization beam splitter misalignment on the proposed 4PM system.Furthermore,the transmission distance could be doubled to*50 km by employing feedback decision equalizers.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.61335005,61325023,and 61401378)
文摘A flexible polarization demultiplexing method based on an adaptive Kalman filter（AKF） is proposed in which the process noise covariance has been estimated adaptively. The proposed method may significantly improve the adaptive capability of an extended Kalman filter（EKF） by adaptively estimating the unknown process noise covariance. Compared to the conventional EKF, the proposed method can avoid the tedious and time consuming parameter-by-parameter tuning operations. The effectiveness of this method is confirmed experimentally in 128 Gb/s 16 QAM polarization-division-multiplexing（PDM） coherent optical transmission systems. The results illustrate that our proposed AKF has a better tracking accuracy and a faster convergence（about 4 times quicker）compared to a conventional algorithm with optimal process noise covariance.
