Secure Optical Communication System Research Articles

Secure optical communication system based on polarization regulation of the data fragmentation multipath transmission technology.

We propose and demonstrate a data fragment multipath transmission scheme to achieve a secure optical communication based on polarization regulation. A dual-polarization Mach-Zehnder modulator (DPMZM) is driven by digital signals which are scattered by field-programmable gate array (FPGA) and transmitted in multiple paths. By utilizing two orthogonal polarization states, we have achieved a signal transmission under different optical parameters, and the transmission rate of the two paths can reach over 10 Gbps through a 20 km fiber with 2.5 Gbps hopping rate. In addition, we establish a theoretical model to analyze the security of the system and simulate brute force cracking; the probability of cracking the minimum information unit is 1.53 × 10-53. This proves that it is difficult to obtain a user data even using the fastest computers. Our scheme has provided, to our knowledge, a new approach for physical layer security.

Research on chaotic secure optical communication system based on dispersion keying with time delay signatures concealment

In response to the possibility of time delay (TD) signatures (TDSs) leakage becoming a serious problem in chaotic optical communication, from the perspective of improving the security of chaotic optical communication, this paper proposes a chaotic secure optical communication system based on dispersion keying, which generates signals with TDSs concealment characteristics. In this scheme, a common laser is used to drive chaotic synchronization between the transmitter and the receiver. The complex chaotic signal is generated by the combination of all-optical feedback and optical injection, and the TDSs are hidden by using the structure of dual filters and setting the parameters of each device reasonably. The switch is controlled by binary message to connect fiber Bragg gratings (FBGs) with different dispersion coefficients and maps different symbols to different chaotic attractors instead of the traditional way of directly sending messages to the channel. In addition, the generated signal no longer suffered from return map attacks. FBGs can compress and expand signals in the time domain to enhance the complexity of chaotic signals, and the dispersion value is an important key to effectively increasing the key space. Finally, the performance of TDSs concealment, sensitivity of parameter mismatch, and return map attack in this scheme are discussed in detail. The scheme still achieves a bit error rate (BER) of 1.74 × 10−4 when transmitting at a rate of 10Gbit/s under harsh communication environments such as 10 dB signal-to-noise ratio (SNR), which provides a reference for realizing high-speed and secure optical communication at the physical layer.

Self-Powered Wide-Narrow Bandgap-Laminated Perovskite Photodetector with Bipolar Photoresponse for Secure Optical Communication.

Perovskite photodetectors with bipolar photoresponse characteristics are expected to be applied in the field of secure optical communication (SOC). However, how to realize the perovskite photodetector with bipolar response remains challenging. Herein, by introducing bismuth iodide (BiI3 ) into Sn-Pb mixed perovskite precursor solution, 2D perovskite FA3 Bi2 I9 is spontaneously formed at the bottom to realize a wide-narrow bandgap-laminated perovskite film. Wavelength-dependent bipolar response is realized based on the absorption difference of the photoactive region with different bandgap combined with the carrier competition of the homotypic transport layer adopted in the as-fabricated photodetector. Under the visible/near-infrared (NIR) light irradiation, the bottom/top of the film generates a higher carrier concentration, where electrons are easier to be separated and transported by the SnO2 /PC61 BM to the bottom/top electrodes, respectively, resulting in a negative and positive bipolar response. Finally, based on positive NIR signal as the effective signal and negative visible signal as the interference signal, the SOC system is realized, where the positive NIR signal is well hidden by the negative visible signal. This work provides a simple and feasible strategy for fabrication of laminated perovskite films to achieve bipolar response.

Precise On-Chip Spectral and Temporal Control of Single-Photon-Level Optical Pulses

The constantly growing need for fast and secure optical communication systems resulted in the rapid development of classical and quantum photonic technologies. Continuous research on improving the capacities of communication channels and the efficiency of optical information processing systems were naturally followed by miniaturization. Photonic integration combined with spectral-temporal multiplexing has led to improvements in communications. In this paper, we present accurate control of temporal and spectral profiles of optical pulses generated at the telecom wavelengths using an indium phosphide-based photonic integrated circuit. The device enables simultaneous temporally and spectrally resolved measurements using single photon counting. We discuss its applications in multidimensional time-frequency quantum key distribution, where security relies on time-frequency uncertainty, and other applications.

Integration of Self-Adaptive Physical-Layer Key Distribution and Encryption in Optical Coherent Communication

We propose and experimentally demonstrate a compatible physical-layer secure optical communication (PLSOC) system that integrates self-adaptive physical-layer key distribution (PLKD) and encryption (PLE) in optical coherent communication. Based on bit error rate difference of QAM signals mapped by asymmetric basis state Y-00 protocol, the secret key can be secretly exchanged over public fiber links without the pre-shared keys. Moreover, we perform a parameter self-adaptive strategy for practical and dynamic PLKD. The security of the key is evaluated in the case of a fiber-tapping attack. A secure hash algorithm, SHA3-512, is used to perform privacy amplification to obtain the virtually secure key. An error-free PLKD rate reaches 39.3 Kbits/s over 300km ultra-low loss fiber. We experimentally enable the integration of the proposed PLKD scheme and quantum noise stream cipher (QNSC) with a single wavelength, same system. Q factor penalty of the integration system compared to the QNSC system is 3.7dB (optical back-to-back) and 4.8dB (300km) respectively. By exploiting a common hardware platform, with the same wavelength, the proposed PLSOC system addresses the problem that PLKD and PLE are separately performed through independent optical fiber links or wavelengths. Since only digital signal processing is used, the scheme does not require extra hardware.

Experimental demonstration of an 8-Gbit/s free-space secure optical communication link using all-optical chaos modulation.

For the first time, to the best of our knowledge, we experimentally demonstrate a high-speed free-space secure optical communication system based on all-optical chaos modulation. The effect of atmospheric turbulence on optical chaos synchronization is experimentally investigated via a hot air convection atmospheric turbulence simulator. It is shown that, even under moderately strong turbulent conditions, high-quality chaos synchronization could be obtained by increasing the transmission power. Moreover, a secure encryption transmission experiment using a high bias current induced chaotic carrier for 8-Gbit/s on-off-keying data over a ∼10-m free-space optical link is successfully demonstrated, with a bit-error rate below the FEC threshold of 3.8 × 10-3. This work favorably shows the feasibility of optical chaotic encryption for the free-space optical transmission system.

Time-Delay Signature Concealment in a Security-Enhanced Optical System With Dual-Loop Electro-Optic Self- Feedback Phase Encryption

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.

56 Gb/s PAM4 physical secure communication based on electro-optic self-feedback hardware temporal phase encryption and decryption.

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.

Design and implementation of cipher algorithm based secure optical communication system

Design and implementation of cipher algorithm based secure optical communication system

Key Space Enhanced Correlated Random Bit Generation Based on Synchronized Electro-Optic Self-Feedback Loops with Mach–Zehnder Modulators

With the widespread application of big data, the amount of data transmitted through optical networks has been increasing dramatically. Correlated random bit generation (CRBG) is one of the key technologies in secure communication systems to ensure security performance and transmission efficiency. We propose and demonstrate a CRBG scheme based on a Mach–Zehnder modulator (MZM) electro-optic feedback loop to improve the security and speed of communication systems. In this scheme, common-signal-induced synchronization is accomplished to generate wideband complex physical entropy sources, and a private hardware module is employed to perform post-processing and nonlinear transformation of the synchronized signal. The simulation results show that the effective bandwidth of the output chaotic signal is significantly increased to 27.76 GHz, and high-quality synchronization with a correlation coefficient of over 0.98 is reached. A high-rate CRBG of up to 5.3 Gb/s is successfully achieved between two synchronized wideband physical entropy sources, and the hardware key space is enhanced to ∼242, which greatly improves the privacy of physical entropy sources. The proposed scheme provides a promising approach for high-speed private CRBG, which is expected to be used in high-speed secure key distribution and optical communication systems.

Photonic-layer secure 56 Gb/s PAM4 optical communication based on common noise driven synchronous private temporal phase en/decryption.

Achieving photonic layer security at the lowest network layer to supplement the upper layer digital cryptography in fiber-optic networks is a constant pursuit but a critical challenge. In this Letter, we propose and experimentally demonstrate a high-speed photonic-layer secure optical communication system based on a novel, to the best of our knowledge, common noise driven synchronous private temporal phase en/decryption scheme, which is capable of supporting high-order modulation formats and enhancing security. A record high bit rate of 56 Gb/s 4-level pulse amplitude modulation (PAM4) confidential signal is successfully encrypted and decrypted by remotely synchronized private noise-like en/decryption signals after secret transmission over 20 km of optical fiber with a bit-error-rate (BER) lower than the hard-decision forward error correction (HD-FEC) limit. The demonstrated scheme may provide a promising way for future ultrahigh-speed photonic-layer secure optical communication.

Assessment of Highly Performance Secure Optical Communication Systems based on Chaotic Design

As optical communication system deployment is expensive, and reconfiguration is occasionally impossible or costly, system experiments and simulations have become necessary for predicting and optimizing system performance. OptiSystem is a cutting-edge optical communication simulation tool for designing, testing, and optimizing nearly any kind of optical connection in the physical layer of a wide range of optical systems. This paper proposed single-mode fiber as a transmitting medium for encrypted data. We examined a Dense Wavelength Division Multiplexing (DWDM) system with eight channels operating at 10 Gbps. A large capacity 80 Gbps system with a frequency range of 193.1 THz–193.8 THz and a Non-Return to Zero (NRZ) modulation format is analyzed in the proposed design. The results show that the proposed scheme can effectively transmit secure data based on new chaotic systems. MATLAB is used to implement the encryption and decryption processes, whereas some statistical analysis and OptiSystem 7 are used to assess the signal transmission in optical fibers. The performance of the proposed system is evaluated in terms of Quality Factor (Q-factor), Bit Error Rate (BER) and eye .diagram. It is observed that by varying the input power from -15 dBm to 15 dBm with step of 5 dBm, a low BER with a high Q-factor has the best values at 5 dBm of input signal power , where the maximum Q-factor is 42.2797, and the minimum BER of 0 is obtained for 100 km of optical fiber length. A slightly degradation in system performance was abserved with increasing of fiber length from 50 km to 125 km.

Experimental demonstration of synchronous privacy enhanced chaotic temporal phase en/decryption for high speed secure optical communication.

Protecting confidential high speed optical signal transmission at the lowest physical layer is a critical challenge for modern fiber-optic communication systems. In this paper, we experimentally demonstrate a novel synchronous privacy enhanced chaotic temporal phase en/decryption scheme for high-speed physical layer secure optical communication. A remote chaos synchronization architecture relying on common source signal driving and private response hardware modules comprising of dispersive components and slave lasers is employed to generate synchronized private chaotic en/decryption signals, and simultaneously suppress residual driving-response correlation for enhancing the security. A proof-of-principle demonstration by secure transmission of a 28 Gb/s on-off-keying modulated confidential signal over 100 km single mode fiber link based on the private chaotic temporal phase en/decryption scheme is successfully achieved. The demonstrated hardware optical en/decryption approach may provide a promising way towards future ultra-high speed physical layer secure optical communication systems.

25 Gb/s Physical Secure Communication Based on Temporal Spreading-Then-Random Phase Encryption

Ensuring high speed physical layer confidential data exchange in classical optical fiber channels is a critical challenge. In this letter, we experimentally demonstrated a physical secure optical communication system based on temporal spreading-then-random phase encryption scheme for secure transmission of 25 Gb/s intensity-modulated signal. Commercial low cost continuous-wave laser is employed as the optical source, and a chirped fiber Bragg grating followed by a phase modulator is utilized as a two-dimensional encryption module. Successful encryption and decryption of 25 Gb/s confidential data have been achieved by optimizing optical hardware parameters. The demonstrated system can combine the advantages of hardware and digital encryption, exhibiting great potential for providing physical layer security in future high-speed secure optical communication systems.

Encrypting A 7.88ghz Frequency Message Within A Chaotic Carrier by Optical Feedback

A new laser system is suggested and experimentally verified as a chaotic transmitter for a secure optical communication system. The laser source kind is a distributed feedback with a peak wavelength 1310nm and maximum power 5mW. A doubly external cavity with 85cm of length is constructed via air.Chaotic signal is achieved successfully after the laser reach of coherence collapse, with a very wide band spectrum (12GHz). This value is capable to increase subjecting to several parameters based on optical feedback (OFB) such as laser current operating level, beam focusing, polarization control, etc. In order to test a message hiding possibility, a frequency message is modulated directly into the laser, which is connected with the laser source using a bias tee. For the free running (solitary) semiconductor laser, the maximum available direct current modulation is: 3GHz/mA, while this value can be increased by this technique. This gives the possibility for very high modulation values and increasing data package volume that can send securely in the applications that requires immunity.

A Novel Optical Frequency-Hopping Scheme Based on a Flexible Structure for Secure Optical Communications

A novel optical frequency-hopping scheme based on a flexible structure for secure optical communications is proposed and demonstrated. In the proposed scheme, critical users' data are divided into a lot of segments, and these segments are transmitted by different optical wavelengths in time domain. In other words, one channel optical carrier carries different users' data segments. A flexible structure was demonstrated and used in optical frequency-hopping system to simplify the structure and decrease the cost of the security system. In this paper, the viability of a four-wavelength-frequency-hopping secure optical communication system with a 25-Gb/s error-free transmission through a 32-km single-mode fiber and a 8-km dispersion compensation fiber was demonstrated and verified by simulation tools.

Confidentiality analysis of optical code-based secure optical communication system

A theoretical model is proposed to analyze the time-domain spectral phase en/decoding and evaluate the unconditional security of the optical code-based secure optical communication systems with DPSK modulation. The confidentiality of the systems with and without bit-by-bit code scrambling technique is investigated. It mathematically proves that the system without code scrambling lacks confidentiality and the system employing code scrambling can realize unconditionally secure transmission. Furthermore, encoding only within the central band of the spectrum is sufficient for perfect secrecy, and the secrecy rate can be potentially improved. It allows the system to operate in the burst mode for code generation and encoding and thus have an idle time for rearm.

QAM Quantum Noise Stream Cipher Transmission Over 100 km With Continuous Variable Quantum Key Distribution

We report the first on-line high-speed and large-capacity secure optical communication system. This was realized by combining a quadrature amplitude modulation/quantum noise stream cipher technology where a coherent multi-level optical signal is hidden in quantum noise and a quantum key distribution technology where secure key delivery is realized with an extremely weak laser light comparable to a single photon. In our security analysis, we adopt a realistic assumption, namely, that an adversary does not have a lossless fiber. To show the advantage of this scheme, we performed a 128 QAM, 70-Gbit/s single-channel transmission over 100 km with a spectral efficiency of as high as 10.3 bits/s/Hz. This is the fastest data rate and highest spectral efficiency yet achieved in quantum cryptography with a realistic assumption.

Secure Optical Communication System Based on Dynamic Strong Dispersion Control

An novel solution for secure optical communication system based on dynamic strong dispersion control is proposed. Firstly, the theoretical principle of dynamic strong dispersion control and the system structure, especially the composition of encryption part and decryption part, are presented. Secondly, the feasibility and performance of the secure system are verified by numerical analyzing in a 40 Gb/s simulation system. Lastly, the huge application potential of this system in various fields is pointed out.

40 Gb/s, secure optical communication based upon fast reconfigurable time domain spectral phase en/decoding with 40 Gchip/s optical code and symbol overlapping

We propose and experimentally demonstrate a 40 Gb/s secure optical communication system with on-off-keying (OOK) modulation format by using a time domain spectral phase en/decoding scheme, which employs a highly dispersive element and high-speed phase modulator for introducing significant symbol overlapping for both the encoded and incorrectly decoded noiselike signals to enhance the information security against eavesdropping using a power detector. The influence of dispersion and chip modulation rate on the symbol overlapping of the incorrectly decoded signal has been analytically investigated and experimentally verified. Security enhancement for 40 Gb/s OOK data using fast reconfigurable 40 Gchip/s optical codes with code lengths of up to 1024 has been demonstrated and compared with a 10 Gb/s system.