VCSELs系统混沌输出的相位时延特征研究

发布时间：2018-05-08 03:02

本文选题：垂直腔面发射半导体激光器(VCSELs) + 混沌　；参考：《西南大学》2015年硕士论文

【摘要】：随着信息技术的飞速发展,人们对信息的高速率、高保密性能有着越来越高的需求。近年来,基于半导体激光器的混沌保密通信因其所展现的巨大应用前景而成为研究者关注的焦点之一。通常情况下,半导体激光器在外部扰动(如外部延迟反馈)下可获得复杂的混沌输出。然而伴随着外部延迟机制的引入,该系统所输出的混沌信号也通常具有了明显的时延特征。这些明显的时延特征给窃密者提供了可利用来破解重构混沌载波的线索,从而使得激光混沌通信的系统安全性受到了威胁。因此,研究半导体激光混沌系统的时延特征具有重要的意义。目前人们对半导体激光混沌系统的时延特征研究大多关注于光场的强度部分(即强度时延特征,I-TDS)。其实半导体激光器输出的光场包含强度和相位两部分。近年来的相关研究发现即使外腔反馈半导体激光器的混沌输出的光场强度时延特征得到了抑制,而其光场相位中的时延特征(P-TDS)还是比较明显的,这仍然给窃密者提供了可能的攻击线索。针对P-TDS问题,目前相关的研究主要集中在DFB激光器构建的混沌系统。而近年来发展迅猛的垂直腔面发射激光器(VCSELs),与DFB激光器相比,具有低阈值电流、高光纤耦合率等独特优势。当前对基于VCSELs的混沌系统的P-TDS研究还非常缺乏。因此,研究基于VCSELs的混沌系统的P-TDS问题,对于获得新型的低时延特征混沌源以及发展高安全性能的混沌保密通信系统都具有重要的意义。基于自旋反转模型,本文分别系统地分析了互耦VCSELs系统混沌输出的P-TDS和主副VCSELs系统混沌输出的TDS及其带宽(BW)。首先,对于互耦VCSELs系统,运用自相关函数(SF)和排列熵(PE)方法,分析了耦合强度、频率失谐对系统混沌输出P-TDS的影响,并与I-TDS进行了比较。研究结果表明：在较弱的耦合强度作用下,混沌I-TDS很弱而P-TDS却比较明显；在合适的耦合强度下,混沌P-TDS和I-TDS可以同时得到抑制。通过进一步考察频率失谐对TDS的影响,确定了互耦VCSELs系统同时输出四路P-TDS和I-TDS均得到有效抑制的混沌信号所需的参数范围。其次,针对主副VCSELs系统,数值研究了系统输出的动力学特性；并分析了注入强度、主激光器(M-VCSEL)与副激光器(S-VCSEL)之间的频率失谐以及M-VCSEL所受到的光反馈强度对系统混沌输出TDS(包括I-TDS和P-TDS)以及输出BW的影响。研究结果表明：在合适的注入强度和频率失谐下,该混沌系统输出的两个偏振分量(X-PC和Y-PC)中的P-TDS和I-TDS均可以得到有效抑制。进一步的,通过分析注入强度对混沌BW的影响,发现在较大负频率失谐区域,系统可输出BW超过30GHz的X-PC和Y-PC混沌信号；结合系统输出混沌的TDS与BW特性,通过选择合适的注入参数,可得到宽带宽、低时延特征的混沌信号输出。此外,在一定的注入强度下,通过合理选择反馈强度,可以显著优化系统的混沌信号输出。
[Abstract]:With the rapid development of information technology, people have higher and higher demand for the high rate and high security of information. In recent years, chaotic secure communication based on semiconductor lasers has become one of the focus of researchers due to its great application prospect. In general, the semiconductor laser can obtain complex chaotic output under external disturbances (such as external delay feedback). However, with the introduction of the external delay mechanism, the chaotic signal output by the system usually has obvious delay characteristics. These obvious time-delay features provide clues to the burglars to decipher and reconstruct chaotic carriers, which threaten the security of laser chaotic communication systems. Therefore, it is of great significance to study the delay characteristics of semiconductor laser chaotic systems. At present, most of the researches on the time delay characteristics of semiconductor laser chaotic systems are focused on the intensity part of the light field (I. e., the intensity delay characteristic / I-TDSs). In fact, the semiconductor laser output field consists of intensity and phase. In recent years, it has been found that even though the optical field intensity delay characteristics of chaotic output of external cavity feedback semiconductor laser are suppressed, the time-delay characteristic of the optical field phase is still obvious. This still gives the snitch a possible clue to the attack. For the P-TDS problem, the current research focuses on chaotic systems constructed by DFB lasers. Compared with DFB lasers, the VCSELs laser with rapid development in recent years has the unique advantages of low threshold current, high fiber coupling rate and so on. At present, the research on P-TDS of chaotic system based on VCSELs is still very scarce. Therefore, it is of great significance to study the P-TDS problem of chaotic systems based on VCSELs for obtaining new low delay characteristic chaotic sources and developing high security chaotic secure communication systems. Based on the spin reversal model, this paper systematically analyzes the TDS and the bandwidth of the chaotic output of the mutually coupled VCSELs system and the primary and secondary VCSELs system, respectively. Firstly, the influence of coupling strength and frequency detuning on the chaotic output P-TDS of the system is analyzed by using the autocorrelation function (SF) and permutation entropy (P) method for the mutually coupled VCSELs system, and the results are compared with that of I-TDS. The results show that the chaotic I-TDS is weak but the P-TDS is obvious under the weak coupling intensity, and the chaotic P-TDS and I-TDS can be suppressed simultaneously under the appropriate coupling intensity. By further investigating the influence of frequency detuning on TDS, the parameter range required for the mutually coupled VCSELs system to output four P-TDS and I-TDS signals simultaneously to suppress chaos effectively is determined. Secondly, the dynamic characteristics of the system output are numerically studied for the principal and secondary VCSELs system, and the injection intensity is analyzed. The frequency detuning between the main laser (M-VCSEL) and the secondary laser (S-VCSEL) and the influence of the optical feedback intensity of M-VCSEL on the chaotic output TDSs (including I-TDS and P-TDSs) and output BW of the system. The results show that the P-TDS and I-TDS in the two polarization components (X-PC and Y-PC) of the chaotic system can be effectively suppressed under the appropriate injection intensity and frequency detuning. Furthermore, by analyzing the effect of injection intensity on chaos BW, it is found that in the larger negative frequency detuning region, the system can output X-PC and Y-PC chaotic signals whose BW exceeds 30GHz, and combines the TDS and BW characteristics of chaos output by the system. By selecting the appropriate injection parameters, the output of the chaotic signal with wide bandwidth and low delay can be obtained. In addition, under a certain injection intensity, the chaotic signal output of the system can be significantly optimized by reasonably selecting the feedback intensity.
【学位授予单位】：西南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN248.4;O415.5

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