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Journal of Optics

A high-speed secure optical communication system based on dual-path electro-optic mutual feedback encryption with time-delay signature concealment

Yuehua An, Yu Guo, Jiangwei Liu, Xulin Gao, Zhensen Gao

Published Jul 1, 2025• 1 citation
Publisher

Abstract

Abstract We propose and numerically demonstrate a novel high-speed physical layer secure optical communication system based on a dual-path mutual feedback phase encryption scheme, which comprises two coupled electro-optic phase modulation feedback branches. The proposed scheme is able to randomly scramble the phase of a confidential message without any additional encryption signal and eliminate the time delay signature (TDS) that exists in a conventional electro-optic phase feedback loop. The TDS concealment is accomplished by the nonlinear transformation produced by the dual-path mutual feedback optical phase encryptor. As a proof-of-principle demonstration, a 32 Gbps differential phase shift keying signal is encrypted and secretly transmitted over a span of 330 km standard single-mode fiber with a bit error rate lower than the hard-decision forward-error correction threshold. Both the sensitive delay time and dispersion values in the feedback loop are employed as hardware keys to guarantee system security. It is envisioned that the proposed scheme may provide an attractive approach for future hardware encryption based high-speed secure optical communication.

DOI
10.1088/2040-8986/adf11c

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Abstract We propose and numerically demonstrate a novel high-speed physical layer secure optical communication system based on a dual-path mutual feedback phase encryption scheme, which comprises two coupled electro-optic phase modulation feedback branches. The proposed scheme is able to randomly scramble the phase of a confidential message without any additional encryption signal and eliminate the time delay signature (TDS) that exists in a conventional electro-optic phase feedback loop. The TDS concealment is accomplished by the nonlinear transformation produced by the dual-path mutual feedback optical phase encryptor. As a proof-of-principle demonstration, a 32 Gbps differential phase shift keying signal is encrypted and secretly transmitted over a span of 330 km standard single-mode fiber with a bit error rate lower than the hard-decision forward-error correction threshold. Both the sensitive delay time and dispersion values in the feedback loop are employed as hardware keys to guarantee system security. It is envisioned that the proposed scheme may provide an attractive approach for future hardware encryption based high-speed secure optical communication.
In this paper, a novel phase encryption scheme based on a dual-loop electro-optic self-feedback structure is proposed for time-delay signature (TDS) concealment. As for a conventional single-loop feedback structure, the TDS is extremely vulnerable to exposure in the common link, resulting in a fatal weakness in the entire security system, whereas, the introduction of an additional feedback branch, brings about the mutual dynamics between the phase feedbacks, and effectively solves the problem. The modulation depth and dispersion values, which are two crucial variables affecting TDS concealment, are investigated in detail. In principle, the scheme is verified to have better robustness, more security, and can supply large key space. Error-free transmission of high-speed signals is possible. Thanks to the aforementioned benefits, the dual-loop electro-optic structure proposed could inspire fresh ideas for secure optical communication systems in the future.
We propose and experimentally demonstrate a novel physical layer encryption scheme for high-speed optical communication. A 10 Gb/s on-off keying signal is secretly transmitted over 100 km standard single-mode fiber. The intensity-modulated message is secured by the encryption mechanism, which is composed of an external noise source and an internal time-delayed feedback loop. The external noise serves as an entropy source with sufficient randomness. The feedback loop structure in the transmitter introduces a time-domain encryption key space, and a corresponding open-loop configuration at the receiver side is used for synchronization and decryption. Experiment results show the effectiveness of the proposed scheme. For a legitimate terminal, bit error rate below 10−8 can be obtained. Decryption degradations with the mismatch of different hardware parameters are researched. The time delay in the feedback loop provides a sensitive encryption key. For other hardware parameters, the system is robust enough for synchronization. Meanwhile, the time-delay signature of the loop is able to be well concealed by the external noise. Moreover, the proposed scheme can support density wavelength division multiplexing transmission with a relatively simple structure. This work also provides a new concept to establish optical secure communication by combining a time-delayed feedback chaotic system and random noise.
Abstract In this paper, a novel secure communication scheme based on temporal spreading and dual-phase perturbation is proposed to improve security at the physical layer. For one thing, the traditional electro-optical feedback phase encryption system is significantly sophisticated by the introduction of additional synchronized chaotic phase encryption. Besides, more keys in this system are available, with the attendance of dispersion and optical chaos, the key space is notably enhanced to ∼2 36 , resisting the eavesdropping attacks. After passing through a series of encryption devices, the information is ultimately displayed as a noise-like signal. A 32 Gb s −1 on-off keying signal is successfully transmitted over a 100 km standard single-mode fiber. Simulation results show that by selecting the appropriate system parameters, a bit error rate as low as 10 −10 can be obtained for legitimate terminals, and the effect of different hardware parameter mismatches on the decryption performance is also investigated which indicates a certain tolerance range for the mismatch of each parameter. This paper provides a new idea to combine an electro-optical feedback system with optical chaos to establish optical secrecy communication.
To guarantee information security from the lowest level of optical networks, it is essential to provide physical layer security in fiber-optic communication systems. However, it is challenging to realize high speed physical secure optical communication based on advanced optical modulation formats and pure commercial hardware components. In this work, we report an experimental demonstration of a high-speed 56 Gb/s PAM4 physical-layer secure optical communication system by employing an electro-optic self-feedback hardware module for temporal self-phase encryption and decryption without consuming any additional encryption channel. An encrypted 56 Gb/s PAM4 confidential signal is successfully decrypted after transmitting over 60 km single-mode fiber. The demonstrated scheme can not only be integrated with existing optical communication networks, but can also be used as a pluggable module, which may provide a promising solution for ultra-high speed physical secure optical communication by combining with advanced multiplexing technology in future.
In the current context of information explosion, securing the physical layer in the backbone networks of coherent optical communication is vitally important. In this letter, we experimentally validate a secure communication scheme for coherent optical communication systems based on electro-optic phase feedback encryption, thereby successfully transmitting a 40 Gb/s dual-polarization quadrature phase shift keying (DP-QPSK) signal over a distance of 180 km. By strategically incorporating a delay line interferometer and a dispersion component within the electro-optic feedback loop, it is possible to generate random phase scrambling at a moderate modulation depth. With the utilization of commercial hardware, the encryption of DP-QPSK signals can be seamlessly accomplished in a plug-and-play manner, removing the necessity for additional synchronization or key distribution systems. The proposed scheme paves a new way to protect the polarization-multiplexing signals and offers a promising approach for secure coherent optical communication system.