In recent years, the generation of wideband l random optical chaos has attracted extensive interest for its extensive applications in the fields of secure communications, radar, and random number generations. In this talk, the presenter demonstrate a novel method for the semiconductor laser-based wideband optical chaos generation with excellent randomness, in virtue of the optical spectrum expansion of self-chaotic-phase-modulation-modulated optical feedback and the phase-to-intensity conversion of nonlinear filtering. It is experimentally demonstrated that, with the proposed method, wideband chaos with flat spectrum can be easily obtained, and simultaneously, the time-delay signature that directly indicates the privacy of chaos source can also be totally suppressed, which means that the physical randomness of chaos is also significantly improved. This paper presents a novel way to generate wideband physical random chaos for the implement of high-speed secure chaotic communication, high-resolution and high-precision radar, and high-rate random bit generation.
In conventional optical communication systems, the transmission signals are regular digital signals. Due to the openness of optical fiber networks, it is rather easy for eavesdroppers to obtain the transmission signals from the public fiber-link and then intercept the message directly. To address this crucial security challenge, in this work we propose a high-speed secure optical communication system in virtue of physical random temporal encryption based on private physical random phase modulation and phase-to-intensity conversion. The proposed physical random temporal encryption is performed by a module composed of a phase modulator (PM) and a chirped fiber Bragg grating (CFBG), and the corresponding decryption is achieved with a similar module composed of an inverse-phase driven PM and an oppositedispersion CFBG. By distributing a constant-amplitude random-phase signal to the local semiconductor lasers deployed in the encryption module and decryption module, a pair of synchronized physical random PM driving signals that are not exchanged on public link can be independently generated, which guarantees the receiver end can correctly decrypt the original transmission message. Our numerical results demonstrate that with the proposed encryption scheme, the regular transmission signal is encrypted as a noise-like signal that can greatly enhance the security of message, and moreover, based on the private synchronized physical random phase modulation, the privacy of encryption and decryption are guaranteed, which prevents the eavesdroppers from intercepting transmission message. This work provides a promising strategy for the implement of high-speed high-security physical-layer optical communication.
In conventional chaos communication systems based on external-cavity semiconductor lasers (ECSLs), messages are embedded into the chaotic carriers and then directly transmitted to the receiver for recovery. Since the modulated chaotic carrier (chaos + message) is directly transmitted in public link, the eavesdropper can easily access it for interception. It has been proved that when the bit rate is relatively low, the message hidden in the chaotic carrier can be intercepted by using a linear filter with a proper cutoff frequency or reconstructing an illegal receiver system based on the injectionlocking effect. We propose and numerically demonstrate a security-enhanced chaos communication system by introducing an optical time-frequency encryption (OTFE) module to convert the modulated chaotic carrier (chaos + message) as an uncorrelated signal before transmission. At the receiver end, a matching optical time-frequency decryption (OTFD) module is adopted to recover the modulated chaotic carrier for the final message recovery. The results demonstrate that, with the OTFE module the modulated chaotic carrier would be transformed as an uncorrelated chaotic carrier with the time delay signature being perfectly suppressed in the time domain. Simultaneously, in the frequency domain, the spectrum of chaotic carrier would be flattened, and the efficient bandwidth of chaotic carrier can be expanded by several times. With respect to conventional chaos communication systems, the proposed scheme shows obviously higher security under the attack scenarios of direct linear filtering and synchronization utilization. The proposed scheme provides a novel way to implement high-security chaos communication.
Chaotic semiconductor laser is a good candidate for secure communication and high-speed true random bit generator, for
its characteristics of broad bandwidth and prominent unpredictability. Based on the synchronization property and true
random bit generation characteristic of chaotic semiconductor lasers, physical secure key distribution is available. In this
work, we majorly show three key distribution schemes stemming from synchronized chaotic semiconductor lasers or
chaos-based key exchange protocol. The numerical results demonstrate that the security of the chaos-synchronization-based
key distribution scheme can be physically enhanced by adopting dynamic synchronization scheme or encrypted
key generation, and that of key distribution with chaos-based key exchange protocol is dependent on the security of the
exchange protocol and finally determined by the difficulty of regeneration the chaos system accurately.
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