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ABSTRACT: We report on the realization of a hybrid chaos-based communication scheme using three chaotic semiconductor ring lasers (SRLs). In this scheme, two slave SRLs (S-SRLs) are identically driven by a master SRL (M-SRL) subject to delayed optical feedback. Under proper conditions, the S-SRLs are completely synchronized with each other due to the symmetric operation, and they are also synchronized with the M-SRL through the injection-locking effect. The results also show that a message encrypted through chaos shift keying at the M-SRL end can be successfully decrypted by the two S-SRLs, while the two uncoupled S-SRLs allow for dual-channel chaos communication when both counterpropagating modes of one S-SRL are encoded with a message.
Applied Optics 03/2013; 52(7):1523-30. · 1.41 Impact Factor
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ABSTRACT: Successful high-speed fiber-optic transmission using a four-chaotic-semiconductor-laser system is numerically demonstrated. The system performance is benefited from the properties of bandwidth enhancement and the implementation of a two-channel scheme. The bit-error rate of the recovered
message is evaluated for different fiber lengths and message bit rates, respectively. In particular, acceptable communication performance can be achieved for a bit rate up to 8 Gb/s when
the fiber length is approximately 60 km. Such a system could lead to high-speed chaos-based encryption/decryption if the fiber transmission module is considered.
IEEE Photonics Technology Letters 06/2012; 24(12):1072-1074. · 2.19 Impact Factor
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ABSTRACT: The effects of unpredictability degree on the chaos synchronization properties of vertical-cavity surface-emitting lasers with variable-polarization optical feedback are investigated numerically. For variable-polarization optical injection, only low-unpredictability chaos can be well synchronized, while high-unpredictability chaos cannot be synchronized even with large injection strength. On the other hand, for the polarization-preserved optical injection, the synchronization quality is hardly affected by the unpredictability degree, and high-quality synchronization can be achieved for both low- and high-unpredictability chaos due to injection locking.
Optics Letters 09/2011; 36(17):3497-9. · 3.40 Impact Factor
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ABSTRACT: We numerically analyze the effect of an injection current on the synchronization and communication features of two chaotic external cavity semiconductor lasers in a closed-loop configuration. The simulation results demonstrate that, by moderately increasing the injection current, the efficient bandwidth of the chaotic carrier would be broadened, high quality chaos synchronization can be preserved, and the communication performance can be enhanced.
Optics Letters 08/2011; 36(16):3197-9. · 3.40 Impact Factor
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ABSTRACT: The chaotic unpredictability of vertical-cavity surface-emitting lasers (VCSELs) with polarization-rotated optical feedback is evaluated quantitatively via the normalized permutation entropy H. The effect of polarization mode competition (PMC) is explored. For weak PMC, the H for X-polarization mode, Y-polarization mode, and total output are close to each other, while for strong PMC, the H for the total output is the highest one, which indicates that the permutation entropy is an effective tool for quantifying chaotic unpredictability of VCSELs and provides valuable information for choosing the proper chaotic carrier.
Optics Letters 02/2011; 36(3):310-2. · 3.40 Impact Factor
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ABSTRACT: The preservability of the chaos synchronization in an intermittent unidirectional coupling semiconductor laser configuration is numerically investigated. By adding additional feedback to the receiver laser, we find that the complete synchronization can be preserved for several tens of nanoseconds after the coupling is cut off, and longer feedback and coupling delays can provide better preservability. Moreover, when the conversion frequency of the coupling is properly high, the synchronization can be preserved all the time. As a consequence of these results, a one-to-two chaos synchronization system is achieved, which provides an opportunity for the implementation of one-to-many and many-to-many chaos synchronization.
J. Opt. Soc. Am. B. 01/2011; 28(5):1062-1066.
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J. Opt. Soc. Am. B. 01/2011; 28(5):1139-1145.
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ABSTRACT: A chaos-based communication scheme allowing for multiaccess message transmission is proposed. In this scheme, two mutually coupled semiconductor lasers (MCSLs) are identically driven by an external cavity semiconductor laser (ECSL). The MCSLs isochronally synchronize with each other through symmetric operation, and they laggardly synchronize to the ECSL through injection-locking. When external modulation is adopted, strong chaos pass filtering effects that are not restricted by the relaxation oscillation frequencies of the MCSLs are observed, which enables us to achieve high bit-rate multiaccess chaos communication. Moreover, the security can be improved by making use of the multiaccess ability. This scheme can be used as a rudiment of chaos communication networks.
IEEE Photonics Technology Letters 06/2010; · 2.19 Impact Factor
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ABSTRACT: The properties of the leader-laggard chaos synchronization (LLCS) in two mutually coupled external-cavity semiconductor lasers are studied systematically. We theoretically analyze the general conditions for the LLCS based on the symmetric operation mechanism and numerically investigate the influences of operation parameters, the mismatch robustness, the chaos pass filtering effects, the communication performance, and the security of the system. It is demonstrated that stable LLCS, which allows simultaneous bidirectional message exchange in virtue of mutual chaos pass filtering effect, can be achieved in a wide operation region; moreover, high-quality LLCS and satisfactory communication performance can be maintained under a relatively large device parameter mismatch. Compared with the isochronal chaos synchronization in the same system, LLCS provides a wider operation region, a better mismatch robustness, and a stronger chaos pass filtering effect. In addition, the investigations on the security of private key message transmission under some potential attacks indicate that the security can be enhanced by increasing the bit rate moderately, exchanging messages with different bit rates, or monitoring the LLCS.
Physical Review E 06/2010; 81(6 Pt 2):066217. · 2.26 Impact Factor
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ABSTRACT: Influences of variable-angle polarization-rotated optical feedback on polarization properties of vertical-cavity surface-emitting lasers (VCSELs) are investigated numerically. For the so-called case A (x polarization) feedback, only the x mode is selected to pass through the feedback loop. As the polarization angle is varied from 0 degrees to 90 degrees, the dominant polarization mode switching can be observed even for fixed feedback strength and bias current. For the so-called case B (xy polarization) feedback, the total outputs of the VCSEL pass through the feedback loop. The polarization property is much different from case A. The dominant polarization mode switching occurs not in the entire range of polarization angles, however, but in the so-called critical angle, from where the intensities of both polarization modes become comparable to each other and keep around constant values, and can be observed. In addition, the complementary properties of intensities between the two polarization modes for both cases are evaluated quantitatively in terms of the defined normalized intensity.
Applied Optics 09/2009; 48(27):5176-83. · 1.41 Impact Factor
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ABSTRACT: Enhanced chaos synchronization communication between vertical-cavity surface-emitting lasers (VCSELs) is investigated numerically, by adopting a polarization communication protocol where one polarization mode is used as the chaotic carrier and the orthogonal polarization mode is used as the disturbed signal. The chaos synchronization quality for the receiver laser (RL) and attacker laser (AL) are analyzed in terms of the cross-correlation coefficient. There are two distinct regions of good synchronization quality in the injection parameters space. In the first region, good synchronization quality can be ensured for both the RL and AL. In the second region, only the RL can realize chaos synchronization. We further discuss the security enhancement by comparing the communication performance between RL and AL for injection parameters within the second region. The results show that successful and robust decoding is only achievable for the RL.
Optics & Laser Technology.
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ABSTRACT: Chaos synchronization and message transmission of a mutually coupled system consisting of two semiconductor lasers (SLs) and a partially transparent mirror (PTM) in between are investigated theoretically. Analytical results show that two types of chaos synchronization schemes, named as isochronal synchronization (IS) and leader/laggard synchronization (LLS), can be achieved by adjusting the reflectivity and position of PTM. By establishing SIMULINK model, numerical simulations illustrate that as the PTM is positioned at the center of two lasers, IS is available when the reflectivity of PTM is moderate. The LLS is achieved when the reflectivity of PTM equals to 0.5, which means feedback strength equals to coupling strength. Its lag time is just determined by the difference of feedback delay time. The investigations of mutual chaos pass filtering (MCPF) effects and the secure chaotic communication simulations indicate that IS allows real-time bidirectional message transmission on a public-channel, while LLS can achieve higher security chaotic communication by using its lag time as cryptography key. The demonstrated system can be used as a rudiment of array chaos communications system.
Optics Communications.
