The Investigations On The Broadband Chaos Synchronization Network Based On VCSELs

With the development of the chaotic secure communication, the chaos synchronization networks which can realize multi-directional chaos communications have been proposed in succession, in these chaos synchronization networks, the bandwidth of chaotic carrier is usually limited to a few GHz mainly due to the low relaxation oscillation frequency of EELs. Therefore, the communication capacities reported in these chaos networks are not beyond10GHz. In order to meet the needs of modern communications for high-capacity, the chaos synchronization networks which can realize larger capacity secret communications are always highly expected. As a new type of semiconductor lasers, the VCSELs not only have the advantages such as low threshold current, single longitudinal-mode operation, large modulation bandwidth, low cost and easy large-scale integration into two-dimensional arrays etc, but also the output includes two orthogonal linear polarization (LP) modes which can be used as two solitary transmission channels, Thus, the chaos synchronization network based on VCSELs have the larger communication capacity.In this paper, the history of the VCSELs development, the structure and the relative performances of the VCSELs are summarized firstly; the basic theory of chaos synchronization based on VCSELs is introduced secondly; at last, after analysis research status about the chaos synchronization networks, a chaos synchronization networks based on VCSELs has been proposed, the bandwidth performances and the broadband chaos synchronization performances have been investigated. The results show that under suitable injection condition, the bandwidths of two LP modes of D-VCSEL can be greatly enhanced compared with that of injection chaos signal from I-VCSEL with optical feedback. After adopting double chaotic optical injection, chaotic signals with much flatter and wider power spectrum can be obtained. Using the bandwidth-enhanced chaos signal from D-VCSEL to drive all R-VCSELs in the broadband chaos network system, two LP modes of R-VCSEL with over50GHz chaos bandwidth can be obtained for suitable injection strength and frequency detuning. Furthermore, based on the investigation of the synchronization performance of this network, an optimum injection parameter space has been given. In the optimum injection parameter space, the cross correlation coefficients between arbitrary two R-VCSELs is almost1and the bandwidths of the two LP modes are over30GHz, at the same time, the cross correlation coefficients between D-VCSEL and R-VCSEL are smaller than0.6. Thus, through selecting proper injection parameters and take the two LP modes as two channels, this broadband chaos network system has a potential of realizing over60GHz high-capacity chaos secret communication.