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Synchronization in semiconductor laser rings  [PDF]
Javier M. Buldu,M. C. Torrent,Jordi Garcia-Ojalvo
Physics , 2006, DOI: 10.1109/JLT.2007.895555
Abstract: We examine the dynamics of semiconductor lasers coupled in a ring configuration. The lasers, which have stable output intensity when isolated, behave chaotically when coupled unidirectionally in a closed chain. In this way, we show that neither feedback nor bidirectional coupling is necessary to induce chaotic dynamics at the laser output. We study the synchronization phenomena arising in this particular coupling architecture, and discuss its possible application to chaos-based communications. Next, we extend the study to bidirectional coupling and propose an appropriate technique to optical chaos encryption/decryption in closed chains of mutually coupled semiconductor lasers.
Experimental Investigation of Chaos Synchronization in DFB Diode Lasers with Unsymmetrical Scheme

YANG Ling-Zhen,ZHANG Xiu-Juan,WANG An-Bang,GUO Dong-Ming,WANG Yun-Cai,

中国物理快报 , 2008,
Abstract: We experimentally generate high dimension chaotic waveforms with smooth spectrum using a distributed feedback (DFB) semiconductor laser with unidirectional fibre ring long-cavity feedback, and implement the stable chaos synchronization when the chaotic light is injected into a solitary DFB laser diode. The synchronization quality is investigated by time-domain and frequency-domain analysis separately. The frequency-domain analysis indicates that the synchronization has higher quality in the high frequency band. The influences of the injection strength and the frequency detuning on the synchronization are measured. Our experimental results show that the robust synchronization can be maintained with the optical frequency detuning from -11GHz to 40 GHz.
Chaos synchronization in injection-locked semiconductor lasers with optical feedback
Liu Yu-Jin,Zhang Sheng-Hai,Qian Xing-Zhong,

中国物理 B , 2007,
Abstract: Based on the rate equations, we have investigated three types of chaos synchronizations in injection-locked semiconductor lasers with optical feedback. Numerical simulation shows that the synchronization can be realized by the symmetric or asymmetric laser systems. Also, the influence of parameter mismatches on chaos synchronization is investigated, and the results imply that these two lasers can achieve good synchronization, with smaller tolerance of parameter mismatch existing.
Experimental Evidence of Slow Spiking Rate in a Semiconductor Laser by Electro-optical Feedback: Generation and Control  [cached]
S. F. Abdalah,Kais Al-Naimee,R. Meucci,N. Al Muslet
Applied Physics Research , 2010, DOI: 10.5539/apr.v2n2p170
Abstract: We report on experimental evidence of generation and control of low spiking events in a semiconductor laser. An experiment has been carried on a semiconductor laser with an electro-optic feedback, set in a parameter range where chaos occurs. The feedback is modulated by 1 kHz and 10 kHz, frequencies, 50mV amplitudes. The dependence of the injected current on the feedback fraction is observed.
Chaos characteristics of the semiconductor laser with double external cavity optical feedback

Zhao Yan-Feng,

物理学报 , 2009,
Abstract: The chaos characteristics of a DFB semiconductor laser subjected to single and double external cavity optical feedback are analyzed experimentally. The results show that the correlation dimension, bandwidth of the chaos generated by one external cavity optical feedback can be expanded by using double external cavity optical feedback. When the laser is subjected to double external cavity optical feedback, the bandwidth with one external cavity feedback is increased from 5.5 GHz to 11 GHz. Correspondingly, the correlation dimension is increased from 2.8 to 3.6. The information of the external cavity length of the chaos generated by double external cavity optical feedback can be masked in the autocorrelation function.
Control of chaos in a delayed feedback semiconductor laser via dual-wedges

Yan Sen-Lin,

物理学报 , 2008,
Abstract: A method of controlling chaos is presented via dual-wedges in a delayed feedback semiconductor laser. The physical model of the laser dynamics is set up under the condition of the dual-wedges control. The optical-length of the transmission of feedback light in the external cavity can be governed by modulating the dual-wedges while the delay time and feedback intensity of the feedback light are varied. The dual-parameter chaos-control of the delay time and feedback intensity can be physically realized. The chaotic laser can be controlled in periodic states and its mean pulse power increased, as shown by numerical simulations.
Dynamics of semiconductor laser with optical feedback: Evolution from low-frequency fluctuations to chaos

Kong Ling-Qin,Wang An-Bang,Wang Hai-Hong,Wang Yun-Cai,

物理学报 , 2008,
Abstract: The low-frequency fluctuations and high-dimensional chaos with 12.2 correlation dimensions were generated experimentally by a semiconductor laser with optical feedback. Extensive experimental and numerical studies were performed to reveal the evolution process from low-frequency fluctuations to chaos. Our results showed that there exists a obvious critical point for the semiconductor laser's bias current. When the bias current Ib is set below 1.03Ith, the peak-to-peak value of the low-frequency fluctuations increases at first and then decreases with the feedback strength decreasing, while its average period keeps decreasing. In this process, the output of the semiconductor laser never goes chaos. However, when the bias current Ib is set beyond 1.03Ith, chaos appears and is persistent in this range. Moreover, the peak-to-peak value of the low-frequency fluctuations increases continuouslly and its duration decreases with the decrease of the feedback strength. Three stages experienced in the process leading from stable emission and low-frequency fluctuation to chaos are established. Numerical simulations are well consistent with the experimental results.
Erasure of Time Delay Signatures in the Output of an Optoelectronic Feedback Laser with Modulated Delays and Chaos Synchronization  [PDF]
E. M. Shahverdiev,K. A. Shore
Physics , 2009,
Abstract: By studying the autocorrelation function of the optoelectronic feedback semiconductor laser output we establish that the signatures of time delays can be erased in systems incorporating modulated feedback time delays. This property is of importance for the suitability of such laser systems for secure chaos-based communication systems. We also make the first report on chaos synchronization in both unidirectionally and bidirectionally coupled multiple time delay chaotic semiconductor lasers with modulated optoelectronic feedbacks.
Control of chaos in an external cavity delay feedback semiconductor laser via modulating the polarizing light

Yan Sen-Lin,

物理学报 , 2008,
Abstract: Control of chaos in an external cavity delay feedback semiconductor laser via modulating the feedback polarizing light is studied. The laser dynamic physical models of the delayed feedback of dual beams with orthogonal polarizating, with parallel polarizations, or with synchronous or arbitrary polarizing directions are presented, respectively. The delay time and feedback quantity of the feedback light can be adjusted by adjusting the mirror and the optical attenuator in the external optical path, or by adjusting the polarization plane of one beam of polarized light with respect to the polarization direction of the other beam, or at an arbitrary polarization direction to the other beam of polarizing light. In all these cases, the chaotic laser can be controlled. Numerical results show that the laser can be conducted to the single cycle or the multi-cycle, and at the same time be in the polarizing oscillation, polarizing anti-oscillation or stable states.
Dynamics of a single-mode semiconductor laser with incoherent optical feedback  [PDF]
Igor V. Koryukin
Physics , 2013, DOI: 10.1364/JOSAB.31.000873
Abstract: A novel model of a semiconductor laser with optical feedback is presented, generalizing Lang-Kobayashi equations to the case of incoherent feedback. The equations are supplemented by a stochastic variable which models random phase difference between the field inside laser cavity and the feedback field. It is shown that for weak-to-moderate feedback the transition from coherent to incoherent feedback leads to replacement of dynamical chaos by almost stationary lasing with slightly fluctuating intensity. Nevertheless, incoherent feedback can lead to chaotic oscillations, but at considerably larger feedback levels.
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