High-quality Chaos Synchronization Research Articles

Bidirectional Dual-Channel Communication Based on Polarization-Division-Multiplexed Chaos Synchronization in Mutually Coupled VCSELs

A bidirectional dual-channel chaos communication scheme based on the synchronization in the linear polarization modes of vertical-cavity surface-emitting lasers (VCSELs) is introduced numerically. In this scheme, two mutually coupled VCSELs are identically driven by a third chaotic VCSEL. It is demonstrated that high quality chaos synchronization in both the XP and YP modes can be achieved simultaneously. With the polarization-division-multiplexing technology and chaos modulation technology, the proposed scheme affords bidirectional dual-channel message transmission on one public link.

Bidirectional chaos communication based on two semiconductor lasers subjected to incoherent optical injection of common-chaotic-signal

Based on the chaotic synchronization between two response semiconductor lasers (RLs) subjected to incoherent optical injection of common-chaotic-signal from a driven laser (DL), a bidirectional chaos communication scheme is proposed, and the chaotic synchronization characteristics and the effects of intrinsic mismatched parameter on the synchronization performances are numerically investigated. The results show that high-quality chaos synchronization between the two RLs can be achieved while the cross-correlation coefficients between the two RLs and the DL are very low under proper operation condition; the intrinsic parameter mismatching between two RLs will destroy the synchronized quality to a certain extent, but the consequence is not severe. Additionally, the bidirectional transmission performances for two messages with 2Gbit/s and the security of the scheme are also analyzed.

Chaos synchronization between arbitrary two response VCSELs in a broadband chaos network driven by a bandwidth-enhanced chaotic signal

A broadband chaos network is proposed and its chaos synchronization performance is investigated. The results show that, using a bandwidth-enhanced chaotic signal (about 42 GHz bandwidth) from a drive vertical-cavity surface-emitting laser (D-VCSEL) to drive all response VCESLs (R-VCSELs) in the broadband chaos network, high-quality chaos synchronization with over 30 GHz bandwidth between two corresponding linear polarization (LP) modes in arbitrary two R-VCSELs can be obtained under optimum injection parameters, while the correlated coefficients between the D-VCSEL and R-VCSELs are low. Taking two LP modes as two different communication channels, this chaos network may possess the potentiality to realize more than 60 GHz high-capacity secret communication based on VCSELs with several GHz of relaxation oscillation frequency.

COMPLEXITY AND SYNCHRONIZATION IN CHAOTIC INJECTION-LOCKING SEMICONDUCTOR LASERS

The chaotic complexity properties of semiconductor lasers in the chaotic synchronization systems are investigated numerically, based on the information theory based quantifier, the permutation entropy (PE). We find that, on the one hand, the degree of complexity for the master laser increases with the feedback strength firstly and then saturate at higher feedback strength, but are hardly affected by the feedback delay. On the other hand, for the slave laser, the complexity degree is closer to that for the master laser when the high quality chaos synchronization is obtained, which shows that, the PE method is a successful quantifier to evaluate the degree of complexity for the chaotic signals in chaos synchronization systems, and can be considered as a complementary tool to observe the synchronization quality.

Influence of injection current on the synchronization and communication performance of closed-loop chaotic semiconductor lasers

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.

Synchronization of bandwidth-enhanced chaos in semiconductor lasers with optical feedback and injection

We experimentally investigate the generation and synchronization of bandwidth-enhanced chaos in a semiconductor laser (drive laser) that is subject to optical injection from another chaotic semiconductor laser (injection laser) with optical feedback. Effective bandwidth enhancement is achieved over 12 GHz, under the condition in which the optical wavelength of the drive laser is positively detuned with respect to that of the injection laser, outside the injection locking range. The bandwidth-enhanced chaotic signal of the drive laser is injected into a third semiconductor laser (response laser) for synchronization. Synchronization of chaos with a bandwidth greater than 12 GHz is observed between the drive and response lasers, under the condition in which the optical wavelength of the response laser is negatively detuned with respect to that of the drive laser, satisfying the injection locking condition. High-quality chaos synchronization is observed within the injection locking range between the drive and response lasers and under the condition of a low relaxation oscillation frequency of the response laser.