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1.
Modulations imposed on a chaotic optical signal generated by a semiconductor laser can be suppressed by injecting the signal into another similar laser under conditions for chaos synchronization. This filter effect could be used to recover messages hidden in chaotic carriers for robust and secure communications. We use a numerical model to examine the filter properties and show that the filter can be described in terms of differences in characteristic transmission functions for imposed signal and chaotic carrier in the output of the synchronized laser. The filter effect is shown to be larger for lower frequencies and decreases as frequencies approach the relaxation oscillation frequency of the laser in the gigahertz regime, similar to the response of steady-state injection-locked lasers to small-signal modulation. The filter properties are confirmed in experiments using both single and multimode lasers. 相似文献
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《Quantum Electronics, IEEE Journal of》2010,46(3):279-284
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《Quantum Electronics, IEEE Journal of》2010,46(2):258-264
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《Quantum Electronics, IEEE Journal of》2008,44(11):1089-1095
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We theoretically studied synchronization of chaotic oscillation in semiconductor lasers with chaotic light injection. Feedback-induced chaotic light generated from a master semiconductor laser was injected into a solitary slave semiconductor laser. The slave laser subsequently exhibited synchronized chaotic output for a wide parameter range with strong injection and frequency detuning within the injection-locking regime. Our numerical simulation revealed that the synchronized slave laser exhibits remarkable phase locking, even for chaotic light injection. Consequently, synchronization in phase fluctuations becomes dominant over intensity fluctuations. We found that there exists a parameter range where the slave can synchronize in phase only, with no intensity synchronization. However, synchronization can be completely destroyed, both in phase and in intensity, when the phase locking becomes unstable due to four-wave mixing or excited resonance oscillation. The phase locking was studied analytically and the correspondence between numerical and analytical results was shown. We also analytically examined chaos synchronization based on a linear stability analysis from the viewpoint of modulation response of injection-locked semiconductor lasers to a chaotic light signal. As a result, we verified that such injection-locking-induced chaos synchronization results from a quasilinear response of the bandwidth-broadened slave laser due to strong optical injection. 相似文献
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多变量耦合实现双环掺铒光纤激光器混沌同步 总被引:5,自引:1,他引:4
根据双环掺铒光纤激光器的理论模型,提出多变量单向耦合法实现混沌同步,对主从系统模型进行数学推导,研究不同参数条件下双环掺铒光纤激光器的混沌同步,得到实现混沌同步的条件,并在Simulink平台下动态仿真。结果表明,衰减系数不同的两个双环掺铒光纤激光器,主激光器通过定向耦合器驱动从激光器,主从系统可以实现精确混沌同步,且随着反馈强度的增大,实现系统混沌同步的时间越短,反馈强度的取值范围由衰减系数和耦合系数确定;选取不同的系统初值,主从系统可实现混沌同步,系统初值对达到混沌同步时间的影响可忽略不计;在主从系统中引入随机高斯噪声,主从系统仍可实现较好的混沌同步。 相似文献
7.
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
8.
Sanchez-Diaz A. Mirasso C.R. Colet P. Garcia-Fernandez P. 《Quantum Electronics, IEEE Journal of》1999,35(3):292-297
We numerically study the synchronization of two chaotic semiconductor lasers in a master-slave configuration. To synchronize the lasers, a small amount of output power from the master laser is injected, after propagating through an optical fiber, into the slave laser. We show that the output of the master laser can be used as a chaotic carrier to encode a digital message which can be recovered after propagating long distances. We also check the robustness of this scheme when the two lasers are slightly different 相似文献
9.
YAN Sen-lin 《光电子快报》2007,3(5):363-367
Chaotic synchronization of injected multiple-quantum-well lasers of optical fiber system and a theoretical model of optical fiber chaotic secure communication system are presented by coupling a chaotic multiple-quantum-well laser synchroniza- tion system and a fiber channel. A new chaotic encoding method of chaos phase shift keying On/Off is proposed for optical fiber secure communications. Chaotic synchronization is achieved numerically in long-haul fiber system at wavelength 1.55 μm. The effect of the nonlinear-phase of fiber is analyzed on chaotic signal and synchronization. A sinusoidal signal of 0.2 GHz frequency is simulated numerically with chaos masking in long-haul fiber analog communication at wavelength 1.55 μm while a digital signal of 0.5 Gbit/s bit rate is simulated numerically with c1haos masking and a rate of 0.05 Gbit/s are also simulated numerically with chaos shift keying and chaos phase shift keying On/Off in long-haul fiber digital communica- tions at wavelength 1.55 μm 相似文献
10.
We demonstrate that two chaotic systems, each made by two coupled semiconductor lasers, can be synchronized using direct-optical feedback. The robustness of the proposed synchronization scheme against mismatch of source parameters and difference in starting conditions is tested by numerical simulations. Applications to secure data transmission are proposed, namely chaotic masking and chaotic shift keying (CSK) 相似文献
11.
Su Hwan Oh Jang-Uk Shin Yoon-Jung Park Sang-Ho Park Ki Soo Kim Sung-Bock Kim Hee-Kyung Sung Yong-Soon Baek Kwang-Ryong Oh 《Photonics Technology Letters, IEEE》2008,20(6):422-424
We propose and demonstrate very compact multiwavelength lasers (MWLs) with a novel configuration designed to remove the mode hopping in the modulation region and separate the wavelength-tuning of each channel for cost-effective optical line termination sources in the wavelength-division-multiplexing passive optical network. The mode hopping of MWLs in the modulation region was eliminated by wavelength trimming using a tuning heater. The MWLs operated successfully in direct modulation for 1.25-Gb/s transmission over 20 km. 相似文献
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Strong optical injection and optical frequency matching have been used to effect an experimental demonstration of two-mode synchronization using a multimode external-cavity chaotic transmitter laser and two single-mode stand-alone receiver lasers. It is shown by means of synchronization diagrams and measured cross-correlation functions that the longitudinal modes of the receiver lasers have been successfully synchronized to frequency matched modes of the transmitter laser operating in the low frequency fluctuation regime. 相似文献
15.
We demonstrate the transmission of uncompressed 4K videos over the photonics-based terahertz (THz) wireless link using a directly modulated distributed feedback laser diode (DFB-LD). For optical heterodyne mixing and data modulation, a DFB-LD was employed and directly modulated with a 5.94-Gb/s non-return-to-zero signal, which is related to a 6G-serial digital interface standard to support ultra-high-definition video resolution. We derived the optimal frequency of the THz carrier by varying the wavelength difference between DFB-LD output and Tunable LD output in the THz signal transmitter to obtain the best transmission performances of the uncompressed 4K video signals. Furthermore, we exploited the negative laser-to-filter detuning for the adiabatic chirp management of the DFB-LD by the intentional discrepancy between the center wavelength of the optical band-pass filter and the output wavelength of the DFB-LD. With the help of the abovementioned methods, we successfully transmitted uncompressed 4K video signals over the 2.3-m wireless transmission distance without black frames induced by time synchronization error. 相似文献
16.
Sungchul Kim Byoungho Lee Dong Hwan Kim 《Photonics Technology Letters, IEEE》2001,13(4):290-292
Chaos synchronization in two separate erbium-doped fiber lasers through a 1.5-km-long fiber is experimentally demonstrated. Two identical erbium-doped fiber lasers are fabricated and modulated by an optical modulator near the relaxation oscillation frequency of the fiber laser. At this frequency, the two fiber lasers generate chaotic carriers. When the synchronization conditions such as cavity length, modulation frequency, and laser characteristics are satisfied, the two chaotic fiber lasers are synchronized 相似文献
17.
A numerical analysis of an optical chaotic transmission system, based on the synchronization of two chaotic lasers, in a master-slave closed loop configuration is presented. At the transmitter, the master chaotic wave is superposed on the information message; at the receiver, the message is recovered by subtracting the synchronized slave chaotic wave from the received signal. The performances are analyzed in terms of the Q-factor, considering two different message modulation formats: the nonreturn-to-zero and the Manchester coding. The Manchester coding shows enhanced performances due to the shift of the signal spectrum to higher frequencies. 相似文献
18.
D.-L. Cheng Tsu-Chiang Yen En-Chi Liu K.-L. Chuang 《Photonics Technology Letters, IEEE》2004,16(6):1435-1437
Mode hopping is characterized by a stochastic exchange of power between two longitudinal modes of a laser, inducing a high-level intensity noise in the laser's output. This investigation proposes an orthogonal-polarization optical feedback (OPF) method to suppress mode hopping in semiconductor lasers. Experimental results indicated that, under some operating conditions, mode hopping could be completely suppressed by an OPF of around -29.3 dB in feedback ratio while the laser was conducted into a single-mode state. Moreover, the mode-hopping region was significantly reduced, enabling the laser's wavelength to be tuned continuously over a wider range. These results can be used to greatly improve the performance of semiconductor lasers. 相似文献
19.
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
20.
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