Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Optics Letters

Unidirectional physical layer secure key distribution in a fiber channel assisted by neural networks

Liuming Zhang, Xinran Huang, Zhi Chai, Zanwei Shen, Weisheng Hu, Xuelin Yang

Published Jul 20, 2022• 17 citations
Publisher

Abstract

Physical layer secure key distribution (PLSKD) in fiber networks provides high-level security originating from the channel uniqueness, while the channel reciprocity is shared between the legal users via bidirectional transmission. To ensure the key consistency, perfect wideband bidirectional optical devices are required for high-speed PLSKD. Here, we propose and demonstrate a unidirectional PLSKD scheme, where the channel reciprocity is reproduced by neural networks (NNs) so that highly correlated key waveforms are generated and shared between the legal users. Experimental results show that an error-free key generation rate (KGR) of 3.8 Gb/s with excellent randomness is achieved for an 11-km standard single-mode fiber (SSMF) channel. The proposed scheme alleviates the stringent requirement of bidirectional channel transmission in high-speed PLSKD and enables the integration of PLSKD and data transmission in the same fiber channel.

DOI
10.1364/ol.466370

Related papers

A 300 km fiber channel mapping using neural networks for Gb/s physical-layer key distribution

Xinran Huang, Xinyong Peng, Liuming Zhang +2 more

Physical-layer secure key distribution (PLSKD) generally acquires highly correlated entropy sources via bidirectional transmission to share the channel reciprocity. For long-haul fiber links, the non-negligible backscattering noise (BSN) and the challenge of bidirectional optical amplification degrade the key generation performances. Since the channel reciprocity can be precisely mapped using neural networks (NNs), unidirectional PLSKD provides a feasible PLSKD for longer fiber links. Here, a final error-free key generation rate (KGR) in unidirectional PLSKD of 3.07 Gb/s is demonstrated over a 300 km fiber link using NNs. Moreover, the channel mapping is analyzed in terms of fiber distance, chromatic dispersion, the nonlinearity of random source, and BSN.

Optics Letters•Dec 6, 2023•10 citations

Coexistence of High-Speed Physical-Layer Key Distribution and Secure Data Transmission in Fiber

Xinran Huang, Xinyong Peng, Liuming Zhang +4 more

Physical-layer secure key distribution (PLSKD) exploiting channel reciprocity and randomness is promising for data security enhancement in fiber, offering an endogenous high key generation rate (KGR) up to Gb/s. The PLSKD provides the integration possibility of key generation and data transmission within the same fiber channel. The coexistence schemes of PLSKD and secure data transmission in fibers are proposed using wavelength division multiplexing (WDM), and full-duplex transmission at the same wavelength. The coexistence schemes are experimentally demonstrated with a 3.4 and 3.25 Gb/s PLSKD, where the encrypted data rate is 15.7 Gb/s, over a 20 km standard single-mode fiber (SSMF) using WDM or full-duplex respectively. The effects of channel spacing using WDM and trade-offs between PLSKD and secure data transmission using full-duplex are fully analyzed. The proposed secure data transmission with PLSKD is classical and fully compatible with current fiber infrastructures.

Journal of Lightwave Technology•Sep 18, 2023•10 citations

Wavelength dependence of fiber channel reciprocity for bidirectional physical-layer key distribution

Xinran Huang, Yunhao Xie, Liuming Zhang +6 more

To share the reciprocity of a single fiber channel in physical-layer secure key distribution (PLSKD), the bidirectional same wavelength (B-SW) transmission system is generally applied. However, the elastic Rayleigh backscattering noise severely degrades key performance after long fiber transmission. Here, the feasibility of a bidirectional wavelength division multiplexing (B-WDM) transmission in a single fiber for high-speed long-range PLSKD is verified, where the wavelength dependence of fiber channel reciprocity is evaluated. PLSKD based on B-WDM in one standard 100 GHz WDM channel is demonstrated, offering a key generation rate of 4.8 Gbps over a 200 km fiber link, providing a 200% increment in terms of key generation rate (KGR) compared with B-SW transmission.

Optics Letters•Apr 10, 2025•3 citations

10 Gb/s physical-layer key distribution in fiber using amplified spontaneous emission

Xinran Huang, Liuming Zhang, Zhi Chai +4 more

High-speed physical-layer secure key generation and distribution (SKGD) schemes via channel reciprocity are achieved using external electro-optical modulation or random source distribution via additional fiber links. Here, we propose and demonstrate an SKGD scheme using the fluctuation of polarization states from an amplified spontaneous emission (ASE) source, without any external electro-optical modulation or additional fiber link. Experimentally, an error-free key generation rate (KGR) of 10.1 Gb/s is achieved over a 10-km standard single-mode fiber (SSMF), with true randomness originating from ASE. Moreover, the single fiber channel can be shared for SKGD as well as data transmission, allowing the integration of the proposed SKGD with the deployed fiber infrastructure.

Optics Letters•Dec 15, 2022•17 citations

High-Speed Long-Range Physical-Layer Key Distribution Assisted by Neural Networks

Xinran Huang, Liuming Zhang, Zhi Chai +3 more

We propose and demonstrate the unidirectional physical-layer secure key generation and distribution in fiber networks using neural networks, with a Gb/s key generation rate demonstrated over 100-km standard single-mode fiber.

Opto-Electronics and Communications Conference (OECC)•Jul 2, 2023•2 citations

2.7 Gb/s Secure Key Generation and Distribution Using Bidirectional Polarization Scrambler in Fiber

Liuming Zhang, Adnan A. E. Hajomer, Weisheng Hu +1 more

A physical-layer secure key generation and distribution (SKGD) scheme in classical fiber channel is proposed and demonstrated using a bidirectional wide-band polarization scrambler (WBPS), to alter rapidly and symmetrically the state of polarization (SOP) for the two counter-propagating optical signals in fiber. Due to the optical channel reciprocity, highly-consistent key bits can be extracted from the correlated SOP fluctuations, while the key secrecy is ensured by the fiber channel uniqueness. A final key generation rate (KGR) of 2.7 Gb/s is demonstrated over 10 km single mode fiber (SMF), where error-free and true randomness of the generated key are achieved after post-processing. The obtained KGR at Gb/s makes a further step towards the implementation of one-time-pad data encryption with perfect secrecy in fiber networks.

IEEE Photonics Technology Letters•Feb 11, 2021•36 citations
Physical layer secure key distribution (PLSKD) in fiber networks provides high-level security originating from the channel uniqueness, while the channel reciprocity is shared between the legal users via bidirectional transmission. To ensure the key consistency, perfect wideband bidirectional optical devices are required for high-speed PLSKD. Here, we propose and demonstrate a unidirectional PLSKD scheme, where the channel reciprocity is reproduced by neural networks (NNs) so that highly correlated key waveforms are generated and shared between the legal users. Experimental results show that an error-free key generation rate (KGR) of 3.8 Gb/s with excellent randomness is achieved for an 11-km standard single-mode fiber (SSMF) channel. The proposed scheme alleviates the stringent requirement of bidirectional channel transmission in high-speed PLSKD and enables the integration of PLSKD and data transmission in the same fiber channel.
Physical-layer secure key distribution (PLSKD) generally acquires highly correlated entropy sources via bidirectional transmission to share the channel reciprocity. For long-haul fiber links, the non-negligible backscattering noise (BSN) and the challenge of bidirectional optical amplification degrade the key generation performances. Since the channel reciprocity can be precisely mapped using neural networks (NNs), unidirectional PLSKD provides a feasible PLSKD for longer fiber links. Here, a final error-free key generation rate (KGR) in unidirectional PLSKD of 3.07 Gb/s is demonstrated over a 300 km fiber link using NNs. Moreover, the channel mapping is analyzed in terms of fiber distance, chromatic dispersion, the nonlinearity of random source, and BSN.
Physical-layer secure key distribution (PLSKD) exploiting channel reciprocity and randomness is promising for data security enhancement in fiber, offering an endogenous high key generation rate (KGR) up to Gb/s. The PLSKD provides the integration possibility of key generation and data transmission within the same fiber channel. The coexistence schemes of PLSKD and secure data transmission in fibers are proposed using wavelength division multiplexing (WDM), and full-duplex transmission at the same wavelength. The coexistence schemes are experimentally demonstrated with a 3.4 and 3.25 Gb/s PLSKD, where the encrypted data rate is 15.7 Gb/s, over a 20 km standard single-mode fiber (SSMF) using WDM or full-duplex respectively. The effects of channel spacing using WDM and trade-offs between PLSKD and secure data transmission using full-duplex are fully analyzed. The proposed secure data transmission with PLSKD is classical and fully compatible with current fiber infrastructures.
To share the reciprocity of a single fiber channel in physical-layer secure key distribution (PLSKD), the bidirectional same wavelength (B-SW) transmission system is generally applied. However, the elastic Rayleigh backscattering noise severely degrades key performance after long fiber transmission. Here, the feasibility of a bidirectional wavelength division multiplexing (B-WDM) transmission in a single fiber for high-speed long-range PLSKD is verified, where the wavelength dependence of fiber channel reciprocity is evaluated. PLSKD based on B-WDM in one standard 100 GHz WDM channel is demonstrated, offering a key generation rate of 4.8 Gbps over a 200 km fiber link, providing a 200% increment in terms of key generation rate (KGR) compared with B-SW transmission.
High-speed physical-layer secure key generation and distribution (SKGD) schemes via channel reciprocity are achieved using external electro-optical modulation or random source distribution via additional fiber links. Here, we propose and demonstrate an SKGD scheme using the fluctuation of polarization states from an amplified spontaneous emission (ASE) source, without any external electro-optical modulation or additional fiber link. Experimentally, an error-free key generation rate (KGR) of 10.1 Gb/s is achieved over a 10-km standard single-mode fiber (SSMF), with true randomness originating from ASE. Moreover, the single fiber channel can be shared for SKGD as well as data transmission, allowing the integration of the proposed SKGD with the deployed fiber infrastructure.
A physical-layer secure key generation and distribution (SKGD) scheme in classical fiber channel is proposed and demonstrated using a bidirectional wide-band polarization scrambler (WBPS), to alter rapidly and symmetrically the state of polarization (SOP) for the two counter-propagating optical signals in fiber. Due to the optical channel reciprocity, highly-consistent key bits can be extracted from the correlated SOP fluctuations, while the key secrecy is ensured by the fiber channel uniqueness. A final key generation rate (KGR) of 2.7 Gb/s is demonstrated over 10 km single mode fiber (SMF), where error-free and true randomness of the generated key are achieved after post-processing. The obtained KGR at Gb/s makes a further step towards the implementation of one-time-pad data encryption with perfect secrecy in fiber networks.