Electro-optical Feedback Research Articles

Electro-Optical Feedback for (Nearly) All-Optical Detection

Electro-Optical Feedback for (Nearly) All-Optical Detection

Investigation on the monolithically integrated chaotic optical transmitting chip based on parallel EAMs.

Chaotic optical communication ensures information security at the physical layer. However, the monolithic integration of lasers and lithium niobate Mach-Zehnder modulators remains a challenge, limiting the progress of integrated chaotic optical communication systems based on an electro-optic feedback. Here, we propose the monolithically integrated chaotic optical transmitting chip based on the parallel EAMs and validate its performance from the perspectives of phase portraits, fast Fourier transform (FFT), probability density function (PDF), largest Lyapunov exponents, and bifurcation. The results demonstrate the feasibility of the chip, which is beneficial for the miniaturization and integration of the system.

Enabling secure high-speed data transmission: Coherent chaotic optical communication with deep learning and electro-optic feedback

Coherent chaotic optical communication represents a present-day technique for attaining excessive-pace, long-distance statistics transmission with first-rate protection. This approach combines deep-gaining knowledge of chaotic synchronization (DLM-CS) models with virtual-sign processing algorithms to counteract fibre transmission impairments, resulting in a sturdy and green communiqu? device. Chaotic indicators are generated through electro-optic feedback, explicitly using Optical Intensity Chaos and Optical Phase Chaos (OIC), facilitated by Mach-Zehnder Modulator and Interferometer (MZM/MZI) modulators. Additionally, device getting to know-primarily based algorithms are hired to mitigate non-linearity in the communiqu? channel. Performance analysis in this context encompasses Bit Error Rate(BER), lengthy-distance communication competencies, chaotic signal periodicity, chaos synchronization, and safety. This technique allows for steady, high-speed facts transmission over prolonged distances, making it an important era for numerous packages, which includes telecommunications and statistics safety.

Generation of visible Raman operation laser by a fiber electro-optical modulator feedback loop

Generation of visible Raman operation laser by a fiber electro-optical modulator feedback loop

High-speed physical layer secure communication scheme based on synchronous chaotic and electro-optic self-feedback dual-phase encryption

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 ∼236, 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.

Hardware fingerprint construction of optical transmitters based on permutation entropy spectrum of chaos for secure authentication

In this paper, an optical transmitter authentication method using hardware fingerprints based on the permutation entropy spectrum (PES) of electro-optic chaos is proposed. By means of permutation analysis of chaotic time series generated by the electro-optic feedback loop, PES is defined and used as the hardware fingerprint of optical transmitters for secure authentication. The time division multiplexing (TDM) module is used to combine the chaotic signal and the message, while the optical temporal encryption (OTE) module is introduced to ensure the security of the fingerprint. At the receiver, the time division demultiplexing (TDD) module and the optical time decryption (TDD) module are introduced to recover the original chaotic signal. The trained support vector machine (SVM) models will then recognize legal and illegal optical transmitters by judging whether the PES of the received chaotic signal is legitimate or not. The simulation and experimental results show that PES of electro-optic chaos has obvious fingerprint characteristics and is sensitive to the feedback delay T in the feedback loop. The authentication system based on PES can recognize both legal and illegal transmitters in optical networks, and the recognition accuracy can reach about 97%. Under the condition of a low signal-to-noise ratio, the authentication system based on the permutation entropy spectrum can still distinguish legal and illegal transmitters effectively. Meanwhile, our scheme has high controllability and flexibility.

Secure WDM communication based on second order differential feedback electro-optical chaotic mutual injection synchronization

An optical phase chaos and mutual injection chaos synchronization scheme based on second order differential feedback electro-optical loop is proposed for chaotic communication. The filtered chaotic waves for mutual injection synchronization and multi-channel signals are transmitted through wavelength division multiplexing (WDM) to realize large-capacity confidential communication. The results show that the bandwidth of the optical chaos is 41.38 GHz, the normalized permutation entropy is 0.999, and the chaos has the performance of time delay suppressing (TDS). This scheme achieves up to 7-channel 25 GBaud 16QAM with the multi-modulus algorithm (MMA) algorithm at OSNR of 25 dB after 100 km transmission. The bit-rate distance of 280,000 Gb/s km is successfully realized by 500 km transmission of 4-channel 35 GBaud 16QAM signals at 25 dB OSNR. The analysis proves that the performance of the second order digital differential electro-optical phase feedback (2nd order DEOP) chaos is better than that of the 1st order DEOP chaos and 3rd order DEOP chaos. The 2nd order DEOP chaos can be generated at a smaller feedback coefficient, the bandwidth of radio frequency chaos is wider, and the TDS suppression is better. This scheme realizes high-speed and large-capacity secure optical chaos communication, which can be widely used in WDM networks and has practical feasibility and application value.

Ultra-wideband chaotic optical communication based on electro-optic differential feedback loop

A differential feedback electro-optical phase chaotic system is proposed to generate ultra-wideband optical chaos and realize high-speed long-distance chaotic communication. The nonlinear dynamics of this differential feedback loop are studied in detail. The numerical results show, firstly, in terms of chaos complexity, the highest permutation entropy of 0.993 and the largest spectral entropy of 0.945 are achieved. Regarding the key hiding, the time delay signature of phase chaos on both the autocorrelation function and delayed mutual information can be completely suppressed, so security can be guaranteed. Secondly, the maximum bandwidth of the radio spectrum is 46.75 GHz in the range of 50 GHz, and the minimum flatness is 1.62 dB/GHz. Finally, the reception of format-transparent messages can be realized by combining co-drive synchronization and coherent demodulation. The 50 GBaud QPSK signal can transmit 2400 km and the 25 GBaud 16 QAM signal can transmit 1500 km at an OSNR of 25 dB. This system realizes ultra-wideband high-complexity chaos and chaotic communication, which can greatly improve the security, transmission distance, and transmission rate of chaotic optical communication.

Fingerprint construction of optical transmitters based on the characteristic of electro-optic chaos for secure authentication.

In this paper, an optical transmitter authentication method using hardware fingerprints based on the characteristic of electro-optic chaos is proposed. By means of phase space reconstruction of chaotic time series generated by an electro-optic feedback loop, the largest Lyapunov exponent spectrum (LLES) is defined and used as the hardware fingerprint for secure authentication. The time division multiplexing (TDM) module and the optical temporal encryption (OTE) module are introduced to combine chaotic signal and the message to ensure the security of the fingerprint. Support vector machine (SVM) models are trained to recognize legal and illegal optical transmitters at the receiver. Simulation results show that LLES of chaos has the fingerprint characteristic and is highly sensitive to the time delay of the electro-optic feedback loop. The trained SVM models can distinguish electro-optic chaos generated by different feedback loops with a time delay difference of only 0.03ns and have a good anti-noise ability. Experimental results show that the recognition accuracy of the authentication module based on LLES can reach 98.20% for both legal and illegal transmitters. Our strategy can improve the defense ability of optical networks against active injection attacks and has high flexibility.

Security-enhanced electro-optic chaotic communication system based on the logistic map feedback and dynamic key

In this paper, a novel electro-optic chaotic system based on the logistic map feedback (EOLM) is proposed. The logistic map is used to introduce additional nonlinear effects into the electro-optic feedback loop. The simulation results show that, with the increase of logistic map iterations N, the bandwidth and permutation entropy of the chaotic output can be significantly increased, and the spectrum is flatter. The time-delay signature (TDS) of the system can be concealed within the appropriate range of values of parameters, which ensures the security of the key. Synchronization results show that the system is not only sensitive to time delay T but is also sensitive to the feedback intensity β, so β is also the key of the system. Utilizing the sensitivity to β, a dynamic EOLM communication system with changing key (DEOLM) is designed. Based on chaotic self-control, the chaotic optical signal is transformed nonlinearly to generate the control signal, which drives the gain coefficient of the amplifier to change dynamically, so as to realize the changing of β. Simulation of communication performance shows that the DEOLM system greatly raises the difficulty for the eavesdropper to crack the message and improves the confidentiality of communication.

Quantum-Inspired Multi-Parameter Adaptive Bayesian Estimation for Sensing and Imaging

It is well known in Bayesian estimation theory that the conditional estimator attains the minimum mean squared error (MMSE) for estimating a scalar parameter of interest. In quantum, e.g., optical and atomic, imaging and sensing tasks the user has access to the quantum state that encodes the parameter. The choice of a measurement operator, i.e. a positive-operator valued measure (POVM), leads to a measurement outcome on which the aforesaid classical MMSE estimator is employed. Personick found the optimum POVM that attains the MMSE= over all possible physically allowable measurements and the resulting MMSE [1]. This result from 1971 is less-widely known than the quantum Fisher information (QFI), which lower bounds the variance of an unbiased estimator over all measurements without considering any prior probability. For multi-parameter estimation, in quantum Fisher estimation theory the inverse of the QFI matrix provides an operator lower bound on the covariance of an unbiased estimator, and this bound is understood in the positive semidefinite sense. However, there has been little work on quantifying the quantum limits and measurement designs, for multi-parameter quantum estimation in a Bayesian setting. In this work, we build upon Personick's result to construct a Bayesian adaptive (greedy) measurement scheme for multiparameter estimation. We illustrate our proposed measurement scheme with the application of localizing a cluster of point emitters in a highly sub-Rayleigh angular field-of-view, an important problem in fluorescence microscopy and astronomy. Our algorithm translates to a multi-spatial-mode transformation prior to a photon-detection array, with electro-optic feedback to adapt the mode sorter. We show that this receiver performs superior to quantum-noise-limited focal-plane direct imaging.

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.

Research on the Performance of Multimode Optical Chaotic Secure Communication System With Multidimensional Keys and a Complex Entropy Source

In this paper, we design an optical chaotic secure communication system with multi-dimensional keys and a complex entropy source, which can allow secure communication working in different modes such as unicast, multicast, and broadcast. In the proposed scheme, amplified spontaneous emission (ASE) noise of the erbium-doped fiber amplifier (EDFA) with sufficient randomness is used as an entropy source to improve the security of the system. And by using the electro-optic delay feedback loops, the key spaces are introduced and the phase distortion is generated, then the data are masked in both phase and intensity fields. As a frequency-dependent group delay (FDGD) module, Gires-Tournois interferometer (G-T I) in the feedback loop can effectively hide the time delay signature (TDS) and achieve additional 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">36</sup> key spaces. The influence of different key mismatches on decryption function is numerically investigated, and the results indicate that the broadband nature of ASE noise makes the TDS a very sensitive encryption key, which increases the difficulty of illegal third parties stealing information. And with the help of the wavelength converter and wavelength division multiplexer, secure communication in various modes is successfully realized, which greatly improves the communication efficiency and is suitable for various security places.

Three-loop electro-optical phase chaotic secure communication system with time-delay signatures concealment and key space enhancement

A novel three loops electro-optical phase (TLEOP) chaotic secure communication system is proposed, which consists of three mutually coupled electro-optical phase chaotic feedback loops. A pseudo-random binary sequence (PRBS) is introduced in the proposed system scheme. The scheme improves the complexity of the chaotic carriers and completely the time-delay signatures (TDSs) of the system with a small feedback gain coefficient that is easy to reach. The PRBS or the original messages and the chaotic carriers are nonlinearly coupled together and participate in the generation of the chaotic carrier which further improves the complexity and the security of the chaotic system. Multiple TDSs effectively enlarge the key space of the system (about 1012). The synchronization performance of the proposed TLEOP system is discussed. The results show that the TDSs are suitable as the secret key of the system because of the high sensitivity of the chaos synchronization to time-delays. Since the mismatch of the feedback gain coefficient caused by environmental changes has little effect on the chaos synchronization, the proposed system has strong robustness. The proposed scheme has great application prospects in chaotic secure communication.

Analysis of Self-Starting Harmonic Mode-Locking in an Electro-Optic-Feedback Laser

The concept of the self-starting harmonic mode-locking (SSHML) by electro-optical feedback in a solid-state laser is studied. Such an operational mode with m equidistant pulses in a laser cavity is controlled by a delayed single negative electro-optical feedback loop which comprises an intracavity electro-optical modulator and a fast high-voltage photodiode mounted directly on it. Analytical expressions for the feedback delay time and the short pulse duration are derived depending on laser parameters. The build-up time of the SSHML process and the limiting gain values are assessed by a high-resolution numerical simulation. For the purposes of accelerator physics, the pulse duration estimations for a set of the widely used Nd and Yb active media are provided. Robustness, high limiting gain and low sensitivity to gain level make SSHML laser an attractive platform for future multi-bunch photoinjector design.

Optical chaotic communication using correlation demodulation between two synchronized chaos lasers

This paper theoretically investigates the scheme of optical chaotic communication based on correlation demodulation between two synchronized semiconductor lasers. In the scheme, a semiconductor laser (SL) system, which is subject to phase conjugation and electro-optical phase modulation feedback, generates optical chaos with high-complexity, simultaneously, the time-delay (TD) signature can be well concealed. We use the digital signal “0” and “1” to control the chaotic signal’s switching between two arms of electro-optical (E-O) switch to indirectly achieve spreading spectrum. Concretely, for the “0” bit, at the cross arm the waveform of the optical chaotic signal is reversed by utilizing the cross gain modulation (XGM) effect of semiconductor optical amplifier (SOA); for the “1” bit, the chaotic signal is exchanged from the cross arm into the through arm. Based on the four-wave mixing (FWM) effect of optical parameter amplifier (OPA), the optical chaotic signal is converted to the same center wavelength as SOA’s output, and then two chaotic sequences are coupled into a channel in turn, as a results, the power of the signal of 5 Gbit/s is uniformly distributed and expanded to about 23.45 GHz bandwidth, thus its power spectrum density (PSD) becomes very low. We numerically demonstrate that this chaotic dynamics between the transmitter and the receiver can be identically synchronized due to coupling. The results indicate that the novel correlation-demodulation-based optical chaotic communication scheme can tolerate a higher noise level, and it can achieve a high-quality communication under lower signal-to-noise ratio (SNR). Compared with the scheme of synchronized error monitor, the correlation demodulation way has better ability for anti-noise interference.

Wideband complex-enhanced bidirectional phase chaotic secure communication with time-delay signature concealment.

A novel bandwidth-enhanced bidirectional phase chaotic secure communication system with time-delay signature (TDS) concealment is proposed and analyzed by numerical simulation. This bidirectional system based on two mutually coupled electro-optic (MCEO) phase feedback loops is driven by a common all-optical (AO) chaotic source. The AO driving source makes the amplitude and phase terms in the Ikeda-based MCEO equation chaotic. Two mutually coupled optoelectronic delayed feedback loops also greatly increase the complexity of the chaotic carrier. By replacing the semiconductor laser in the existing bidirectional communication scheme with an electro-optic feedback loop, the problems of narrow carrier bandwidth and poor synchronization performance can be compensated. Compared to the single MCEO system, the permutation entropy of the AO-MCEO cascaded system with a bit rate of 10 Gbit/s is improved by 0.13 to 0.98. The TDS of the AO-MCEO system is suppressed 35 times to less than 0.01 to be completely hidden when the EO gain is reduced by half to 2.75. The chaos effective bandwidth is increased by 5 GHz to 32.05 GHz, and the spectrum flatness is reduced by 0.33 dB/Hz to 0.82 dB/Hz. Meanwhile, the security is further enhanced by reducing the cross-correlation coefficient to 0.001 between the AO driving source and the electro-optical chaotic carrier. The results show that the proposed model has potential applications in bandwidth-enhanced bidirectional secure chaotic systems.

Key space enhancement of a chaos secure communication based on VCSELs with a common phase-modulated electro-optic feedback.

In this paper, a novel chaotic secure communication system based on vertical-cavity surface-emitting lasers (VCSEL) with a common phase-modulated electro-optic (CPMEO) feedback is proposed. The security of the CPMEO system is guaranteed by suppressing the time-delay signature (TDS) with a low-gain electro-optic (EO) feedback loop. Furthermore, the key space is enhanced through a unique secondary encryption method. The first-level encrypted keys are the TDS in the EO feedback loop, and the second-level keys are the physical parameters of the VCSEL under variable-polarization optical feedback. Numerical results show that, compared to the dual-optical feedback system, the TDS of the CPMEO system is suppressed 8 times to less than 0.05 such that they can be completely concealed when the EO gain is 3, and the bandwidth is doubled to over 22 GHz. The error-free 10 Gb/s secure optical transmission can be realized when the time-delay mismatch is controlled within 3 ps. It is shown that the proposed scheme can significantly improve the system performance in TDS concealment, as well as bandwidth and key space enhancement, which has great potential applications in secure dual-channel chaos communication.

Reconfigurable Optical Boolean Function Generator Based on Electro-Optical Nonlinear Dynamics

We propose an optical Boolean function generator based on an electro-optical nonlinear feedback loop. Theoretically, all possible Boolean functions with optical input and output can be implemented by passing through enough iterations. By changing the control signal, the optical circuit can be configured to any desired Boolean function without adjusting the physical setup. Optical components with high bandwidth can improve the computing speed markedly. The impact of noise on the system is considered in detail. The results show that a substantial number of reliable Boolean functions can be obtained in the presence of noise contamination. Compared with traditional optical digital computation systems, the proposed scheme exhibits a huge advantage in multifunctional computing and flexible configuration.

WDM-based bidirectional chaotic communication for semiconductor lasers system with time delay concealment

In this paper, we propose a wavelength-division-multiplexing (WDM)-based chaos communication configuration allowing for the bidirectional exchange of information. In the scheme, the output of a master semiconductor laser (MSL), is injected into slave semiconductor lasers (SSLs), drives the chaotic synchronization of SSLs with optical feedback and electro-optical phase feedback. By calculating the largest Lyapunov exponent (LLE), Lempel–Ziv complexity (LZC) and permutation entropy (PE), we find that the system can generate the chaotic signal with high complexity. We also demonstrate that the chaotic signal bandwidth obtained is as high as 24.68 GHz by selecting the suitable parameters; this configuration intrinsically conceals the electro-optical phase feedback time delay signature (TDS) and optical feedback TDS in transmitted variable; this delayed chaotic dynamics are identically synchronized when the parameters of emitter are exactly matched with that of receiver; while the external and internal parameters’ mismatch between emitter and receiver can lead to the decrease of the synchronization quality. In addition, the result reveals that the channel spacing has influence on cross-correlation coefficient (XCF) quantifying synchronization quality. At last, the messages introduced at two ends of the link can be successfully encrypted and decrypted, and we quantitatively analyze the corresponding Q-factor at different transmission rates.