共查询到20条相似文献,搜索用时 15 毫秒
1.
Shibasaki N. Uchida A. Yoshimori S. Davis P. 《Quantum Electronics, IEEE Journal of》2006,42(3):342-350
We numerically investigate the detailed characteristics of chaos synchronization in semiconductor lasers subject to polarization-rotated optical feedback. The emission of the dominant TE mode of a drive laser is rotated 90 deg and fed back to the laser with time delay. The polarization-rotated TE mode is also injected with time delay into the TM mode of a second laser. Two types of synchronization with different time-lags are found, as in the case for synchronization in semiconductor lasers with nonrotated optical feedback. However, a significant difference to the nonrotated optical feedback case is that neither of the two types of synchronization requires matching of optical carrier frequency between the two lasers. 相似文献
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Anticipating synchronization based on optical injection-locking in chaotic semiconductor lasers 总被引:3,自引:0,他引:3
Numerical studies for anticipating chaos synchronization in semiconductor lasers with optical feedback are presented. Anticipating chaos synchronization in a delay-differential system is believed to occur when all chaos parameters between the two systems are perfectly coincident with each other. However, we find new schemes of anticipating chaos synchronization when the parameters between the two systems have mismatches. Under these conditions, the time lag between the two laser outputs is equal to that of anticipating chaos synchronization, but the physical origin of the phenomenon comes from optical injection-locking or amplification in laser systems. We show the evidence of such chaotic synchronization using trajectories in the phase space of the phase difference and the carrier density in the laser oscillations. 相似文献
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Synchronized chaotic optical communications at high bit rates 总被引:7,自引:0,他引:7
Jia-ming Liu How-foo Chen Shuo Tang 《Quantum Electronics, IEEE Journal of》2002,38(9):1184-1196
Basic issues regarding synchronized chaotic optical communications at high bit rates using semiconductor lasers are considered. Recent experimental results on broadband, high-frequency, phase-locked chaos synchronization, and message encoding-decoding at 2.5 Gb/s are presented. System performance at a bit rate of 10 Gb/s is numerically studied for the application of three encryption schemes, namely chaos shift keying, chaos masking, and additive chaos modulation, to three chaotic semiconductor laser systems, namely the optical injection system, the optical feedback system, and the optoelectronic feedback system. By causing synchronization error in the forms of synchronization deviation and desynchronization bursts, the channel noise and the laser noise both have significant effects on the system performance at high bit rates. Among the three laser systems, the optoelectronic feedback system has the best performance while the optical feedback system has the worst. Among the three encryption schemes, only the performance of additive chaos modulation with low-noise lasers is acceptable at high bit rates. 相似文献
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Chaos synchronization and chaotic signal masking in semiconductor lasers with optical feedback 总被引:7,自引:0,他引:7
Theoretical and experimental investigations of chaos synchronization and its application to chaotic data transmissions in semiconductor lasers with optical feedback are presented. Two schemes of chaos synchronization-complete and generalized synchronization-are discussed in the delay differential systems. The conditions for chaos synchronization in the systems and the robustness for the parameter mismatches are studied. The possibility of secure communications based on the chaos masking technique in semiconductor lasers with optical feedback is also discussed, and message transmission of a 1.5-GHz sinusoidal signal is demonstrated. The method of bandwidth enhancement of chaotic carriers is proposed for broad-band chaos communications. 相似文献
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Abarbanel H.D.I. Kennel M.B. Illing L. Tang S. Chen H.F. Liu J.M. 《Quantum Electronics, IEEE Journal of》2001,37(10):1301-1311
Semiconductor lasers provide an excellent opportunity for communication using chaotic waveforms. We discuss the characteristics and the synchronization of two semiconductor lasers with optoelectronic feedback. The systems exhibit broadband chaotic intensity oscillations whose dynamical dimension generally increases with the time delay in the feedback loop. We explore the robustness of this synchronization with parameter mismatch in the lasers, with mismatch in the optoelectronic feedback delay, and with the strength of the coupling between the systems. Synchronization is robust to mismatches between the intrinsic parameters of the lasers, but it is sensitive to mismatches of the time delay in the transmitter and receiver feedback loops. An open-loop receiver configuration is suggested, eliminating feedback delay mismatch issues. Communication strategies for arbitrary amplitude of modulation onto the chaotic signals are discussed, and the bit-error rate for one such scheme is evaluated as a function of noise in the optical channel 相似文献
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We propose and demonstrate a scheme for generating synchronized chaotic mode hopping in two wavelength-tunable lasers. Chaotic mode hopping resulting in large hops in wavelength is induced by delayed feedback of an electrical signal proportional to the intensity of the laser output which passes through an optical filter. Mode hopping among up to 11 modes was experimentally observed and optical signals in each wavelength band show a different on-off modulation time series. Analysis of the time series indicates high dimensionality. By using a unidirectional coupling method that injects part of the output of one laser into another, we can synchronize the chaotic mode hopping of two separate lasers and obtain synchronized chaotic on-off modulation patterns in multiple corresponding wavelength bands. The robustness of the synchronization with respect to the parameter mismatch and the effects of the coupling strength are investigated. The chaotic mode hopping dynamics and synchronization are well described with a numerical model that includes the characteristics of the laser tuning and the filter transmission. A multiplexed data transmission scheme using chaotic carriers is proposed and experiments demonstrate that multiple messages can be simultaneously recovered when chaos synchronization is achieved 相似文献
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《Quantum Electronics, IEEE Journal of》2010,46(2):258-264
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External optical feedback sensitivity in distributed feedback (DFB) semiconductor lasers is analyzed with special attention to phase-shifted and complex-coupled lasers. The effects of various structural parameters such as coupling strength, facet reflectivity, and corrugation phase angle on external optical feedback sensitivity are studied. The λ/4 phase-shifted index-coupled DFB laser exhibits low external optical feedback sensitivity for large index-coupling coefficient and high facet reflectivity. Pure gain-coupled DFB lasers perform better than the phase-shiftless uniform index-coupled DFB lasers but worse than λ/4 phase-shifted index-coupled lasers with high coupling strengths. External optical feedback sensitivity of complex-coupled lasers depends significantly on the index-to-gain coupling ratio, the phase between the index and gain gratings, and the total coupling 相似文献
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We numerically study the synchronization or entrainment of two unidirectional coupled single-mode semiconductor lasers in a master-slave configuration. The emitter laser is an external-cavity laser subject to optical feedback that operates in a chaotic regime. The receiver can either operate at a chaotic regime similar to the emitter (closed-loop configuration) or without optical feedback and consequently under continuous-wave conditions when it is uncoupled (open-loop configuration). We compute the degree of synchronization of the two lasers as a function of the emitter-receiver coupling constant, the feedback rate of the receiver, and the detuning. We find that the closed-loop scheme has, in general, a larger region of synchronization when compared with the open loop. We also study the possibility of message encoding and decoding in both open and closed loops and their robustness against parameter mismatch. Finally, we compute the time it takes the system to recover the synchronization or entrainment state when the coupling between the two subsystems is lost. We find that this time is much larger in the closed loop than in the open one. 相似文献
13.
Satyan N. Wei Liang Aflatouni F. Yariv A. Kewitsch A. Rakuljic G. Hashemi H. 《Photonics Technology Letters, IEEE》2008,20(11):897-899
In this letter, we demonstrate the use of an electronic feedback scheme using a voltage controlled oscillator (VCO) to control the optical phase of individual semiconductor lasers (SCLs) phase locked to a common reference laser using heterodyne optical phase-locked loops (OPLLs). The outputs of two external cavity SCLs phase-locked to a common reference laser are coherently combined, and the variation in the relative optical path lengths of the combining beams is corrected by dynamically changing the phase of the offset radio-frequency signal fed into one of the OPLLs by means of a VCO. A stable power combination efficiency of 94% is achieved. This inherently different method of phase control, i.e., electronic rather than the use of electrooptic crystals, is deemed essential for new applications involving coherent optoelectronics. 相似文献
14.
本文提出光纤混沌双向保密通信设想,通过耦合光注入半导体激光器激光混沌全光耦合反馈同步系统和光纤传输信道,建立了光纤混沌双向通信系统模型,数值实现了该系统在长距离光纤传输中的同步,详细地分析了系统同步时间随光纤传输长度的关系.证明了光纤的交叉相位调制是限制激光混沌在光纤传输中同步的主要原因,导出了系统传输的非线性相移.数值模拟了具有正弦调制信号的调制频率0.5GHz混沌模拟通信和数字信号调制速率0.4Gbit/s以及20Gbit/s的混沌数字通信以及调制速率0.05Gbit/s 混沌键控通信的应用,计算出光纤混沌数字通信速率和同步误差等关系,还特别分析了系统解码特性和调制带宽,表明系统具有非常好的保密性能和具有高速率通信的能力.光纤混沌双向保密通信是可以实现的. 相似文献
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《Lightwave Technology, Journal of》2010,28(4):526-538
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Sivaprakasam S. Spencer P.S. Rees P. Shore K.A. 《Quantum Electronics, IEEE Journal of》2002,38(9):1155-1161
Chaotic synchronization is investigated experimentally using two diode lasers as transmitter and receiver. The transmitter laser is rendered chaotic by application of an optical feedback in an external-cavity configuration. Experimental conditions are found under which the synchronization diagram makes a transition from a positive to a negative gradient. A regime of operating conditions is identified in which the receiver laser is found to anticipate the dynamics of the transmitter laser. The anticipation time does not depend on the external-cavity length, but rather on the time of flight between the two lasers. Changes in the spectrum of the synchronized system are shown to be associated with the transition between anticipating and lag synchronization. 相似文献
17.
Demultiplexing chaos from multimode semiconductor lasers 总被引:3,自引:0,他引:3
We show numerically that the injection of two chaotic modes of a multimode semiconductor laser with optical feedback into two single-mode stand-alone semiconductor lasers leads to chaotic synchronization between the respective intensities. The effect of parameter mismatch between the transmitter and receiver lasers is examined, and it is concluded that the observed synchronization is a consequence of injection locking. Under these conditions, the possibility of using this demultiplexing scheme for message transmission is examined. 相似文献
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Starting from Fresnel diffraction theory, we derive analytic expressions for the lateral spatial dependence of feedback fields for the cases of conventional and phase-conjugate optical feedback. By using numerical simulations we show that for narrow-stripe gain-guided lasers, both types of optical feedback from an external cavity can convert the twin-lobed far fields into a nearly single-lobed far field. We also find that conventional and phase-conjugate feedbacks in broad-area lasers induce a spatial modulation of the lateral field that increases the tendency for filamentation at moderate (-30 dB) feedback levels 相似文献
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A model of self-pulsation in two-section distributed feedback (DFB) lasers without a saturable absorber is developed by using generalized rate equations. The introduction of an effective differential gain in our model allows us to take into consideration both material and structural effects. The self-pulsation conditions are derived from a linear stability analysis. A mechanism based on a negative effective differential gain is proposed to explain the origin of self-pulsation in such lasers. By considering an injected optical signal, the optical synchronization of self-pulsating lasers is studied using nonlinear simulations. This leads to the determination of some locking-range properties, which are then compared to experimental and analytical results 相似文献