Xiao-Dong Lin

Time delay signature concealment of optical feedback induced chaos in an external cavity semiconductor laser

The time delay (TD) signature concealment of optical feedback induced chaos in an external cavity semiconductor laser is experimentally demonstrated. Both the evolution curve and the distribution map of TD signature are obtained in the parameter space of external feedback strength and injection current. The optimum parameter scope of the TD signature concealment is also specified. Furthermore, the approximately periodic evolution relation between TD signature and external cavity length is observed and indicates that the intrinsic relaxation oscillation of semiconductor laser may play an important role during the process of TD signature suppression.

Isochronous Synchronization Between Chaotic Semiconductor Lasers Over 40-km Fiber Links

A long-distance isochronous chaos synchronization system, composed of a driving chaotic semiconductor laser and twin semiconductor lasers, is demonstrated experimentally. Via a driven chaotic signal which is generated by the driving chaotic semiconductor laser subject to external feedback and then injects into the twin semiconductor lasers by a pair of 20-km single-mode fibers, respectively, isochronous synchronization between the twin semiconductor lasers is experimentally observed. Further results show that high-quality isochronous synchronization can still be maintained even though the correlation coefficient between the driving laser and twin lasers is low. In addition, the bandwidth of synchronized chaotic signals is enhanced to more than 10 GHz although the bandwidth of driving signal is about 5.7 GHz.

Simultaneous Generation of Two Sets of Time Delay Signature Eliminated Chaotic Signals by Using Mutually Coupled Semiconductor Lasers

Simultaneous generation of two sets of time delay (TD) signature suppressed chaotic signals is experimentally demonstrated by using a mutually delay-coupled semiconductor laser (MDC-SL) system. The experimental results show that under proper conditions, TD signatures of chaotic output signals in such a system can be eliminated, and two sets of low TD signature chaotic signals can be simultaneously obtained. Furthermore, both the TD signature evolution pattern and the optimum scope for TD signature elimination are experimentally specified by modulating the coupling strength and adjusting frequency detuning between the two mutually coupled lasers.

Chaos synchronization in mutually coupled semiconductor lasers with asymmetrical bias currents

We experimentally and numerically investigated the chaos synchronization characteristics of mutually coupled semiconductor lasers (MCSLs) with asymmetrical bias currents. Experimental results show that, asymmetrical bias current level of two MCSLs has obvious influence on chaos synchronization between them, and stable leader-laggard chaos synchronization can be realized under relatively large asymmetrical bias current levels. Moreover, the influences of frequency detuning and mutually coupling strength between the two lasers on chaos synchronization performance have also been discussed. Theoretical simulations basically conform to our experimental observations.

Bidirectional chaos communication between two outer semiconductor lasers coupled mutually with a central semiconductor laser

Based on a linear chain composed of a central semiconductor laser and two outer semiconductor lasers, chaos synchronization and bidirectional communication between two outer lasers have been investigated under the case that the central laser and the two outer lasers are coupled mutually, whereas there exists no coupling between the two outer lasers. The simulation results show that high-quality and stable isochronal synchronization between the two outer lasers can be achieved, while the cross-correlation coefficients between the two outer lasers and the central laser are very low under proper operation condition. Based on the high performance chaos synchronization between the two outer lasers, message bidirectional transmissions of bit rates up to 20 Gbit/s can be realized through adopting a novel decoding scheme which is different from that based on chaos pass filtering effect. Furthermore, the security of bidirectional communication is also analyzed.

Experimental Observation of Current-Induced Bistability in a Semiconductor Laser With Positive Optoelectronic Feedback

Bistability in a single-mode distributed feedback semiconductor laser (DFB-SL) with positive optoelectronic feedback (POEF) is observed experimentally. For a given biased current, the output dynamical states of DFB-SL with POEF are critically dependent on variation routes of the laser-biased current. Different routes of biased current variation lead to a bistability characterized by states of different time series, power spectra, and phase portraits.

Current-driven state-bistability and power-bistability in a DFB semiconductor laser subject to optical injection

In this paper, current-driven state-bistability and power-bistability in a distributed feedback (DFB) semiconductor laser (LD) subject to external optical injection have been investigated experimentally. The results show that, by sweeping the bias current of slave LD along different routes nearby the threshold, both the power-bistability and the state-bistability between locking and bimodal regime can be observed under the suitable injection power, but these bistable phenomena will disappear under much large injection power. Additionally, the dependence of the width of the state-bistablility loop on the injection power has been discussed.

All-optical generation and linewidth narrowing of tunable photonic microwave based on nonlinear dynamics of semiconductor lasers

Based on the period-one nonlinear dynamical state of an optically injected semiconductor laser, an all-optical method for photonic microwave generation is proposed and investigated experimentally. Experimental results show that through jointly adjusting injected optical strength and frequency detuning between the injected light and the solitary laser, a photonic microwave signal with a tunable frequency range of several tens GHz can be acquired. Via by introducing an optical feedback and properly selecting the feedback strength, the linewidth of photonic microwave can be narrowed about two orders of magnitude.

Further discussion on bandwidth-enhanced chaos synchronization communication based on mutually coupled VCSELs

A bandwidth-enhanced chaos synchronization communication system is proposed and its communication performance is investigated numerically. The results show that, using a bandwidth-enhanced chaotic signal from a driving vertical cavity surface-emitting laser (D-VCSEL) to drive two mutually coupled VCSELs (MC-VCSELs), the high-quality isochronal chaos synchronization with over 30GHz bandwidth between two corresponding LP modes in the two MCVCSELs can be obtained. Taking two LP modes as two different communication channels and adopting chaos masking (CMS) encryption scheme, this system can realize the bidirectional dual-channel high-speed chaos communication at 10Gbits/s transmission rate. Moreover, the parameters mismatches tolerance of this communication system and the influence of message transmission rate on the communication performance also are discussed.

Experimental observations of bistable characteristics of an optically injected semiconductor laser biased nearby the threshold current

In this paper, a new style state-bistability has been experimentally observed by back and forth sweeping the current of a semiconductor laser nearby its threshold. Moreover, the influence of the injection power on the width of state-bistability loop has been analyzed and discussed in detail.