Investigating On The Bidirectional Dual-channel Chaos Synchronization And Communication Based On Mutually Coupled VCSELs With Optical Feedback

As one of the micro-cavity semiconductor lasers, vertical-cavity surface-emitting lasers (VCSELs) exhibit many advantages, compared with traditional edge-emitting semiconductor lasers (EELs), such as low threshold current, intrinsically single-longitudinal mode, circular output beam with narrow divergence, large-scale integration into two-dimensional arrays and low cost. In recent years, chaos synchronization and secure communication based on VCSELs have attracted considerable interests. The output of VCSELs may exists two orthogonal linear polarization modes (i. e.,x-and y-LP mode) because of the weak material and cavity anisotropies, which make it possible to realize dual-channel communication. At present, based on VCSELs, many investigations are focus on single-channel and unidirectional chaos synchronization and communication, but investigations on bidirectional dual-channel chaos synchronization and communication are rare.In this paper, a novel dual-channel chaos security communication system based on mutually coupled VCSELs with optical feedback has been proposed, and chaos synchronization characteristics for each LP mode and the total intensities, together with the influence of mismatched parameters on the synchronization quality, are analyzed based on spin-flip model (SFM). Finally, the communication performances of dual-channel messages encoded in two LP modes have been briefly examined under chaos masking (CMS) and additive chaos modulation (ACM) encryption scheme. The results show that, when the parameters of two lasers are identical, high quality and stable zero-delay chaotic synchronization can be obtained for each LP mode as well as the total intensities. The synchronization quality will decrease with the increase of the parameters mismatching degree, and keep a certain extent tolerance to intrinsic mismatched parameters. However, the synchronization quality is very sensitive to the frequency detuning between the two VCSELs. For 500 Mbits/s messages, it can be extracted successfully upon x-and y-LP modes respectively under ACM scheme, but cannot be recovered under CMS scheme. Additionally, the communication performance will be affected by the mismatched parameters, but the effect is not serious.