發(fā)布時間：2018-10-05 11:54

【摘要】：基于半導體激光器所產(chǎn)生的混沌光信號因在混沌保密通信、混沌雷達、真隨機數(shù)的產(chǎn)生以及時域反射器等諸多領域的應用受到廣泛的關注。通常,半導體激光器主要通過引入光反饋、光電反饋、光注入和電流調(diào)制等外部擾動方式來獲取混沌信號。其中,光反饋方式因結構簡單、易于集成、成本較低、容易控制等特點而成為產(chǎn)生混沌光信號的主要方法。但基于光反饋方式獲取的混沌信號帶寬通常僅有幾GHz且具有明顯的延時特征(TDS)。這不僅限制了混沌保密通信的信息傳輸速率,且大大降低了系統(tǒng)通信的安全性。因此,研究獲取TDS明顯抑制的、頻譜平坦的寬帶混沌信號的相關理論和技術具有重要的意義。本文提出了利用由高非線性光纖(HNLF)和光纖耦合器(FC)構成的高非線性光纖環(huán)路鏡(HNFLM)獲取TDS被明顯抑制的寬帶混沌信號的方法。利用標準帶寬、自相關函數(shù)(ACF)的方法,理論研究了HNFLM對光反饋作用下分布反饋半導體激光器(DFB-SL)輸出的混沌信號的帶寬及其TDS的影響。研究結果表明:當光反饋DFB-SL產(chǎn)生的混沌光信號通過由功分比(PSR)為7:3的FC以及長度為35 M的HNLF構成的HNFLM后,混沌信號帶寬由12.3 GHz提高到41.2 GHz,且其時間序列的ACF在延遲時間附近的最大值σ從0.22減少至0.05�；煦缧盘枎捲鰪娨约癟DS抑制的效果與入射混沌信號的平均功率、高非線性光纖長度、光纖耦合器的PSR有關。其中,混沌信號延時特征主要受PSR的影響。此外,我們繪制了在光纖耦合器的PSR為7:3時,混沌信號帶寬及TDS在混沌信號的平均功率、高非線性光纖長度構成的參數(shù)空間內(nèi)的分布圖譜,確定了利用高非線性光纖環(huán)路鏡獲取低TDS的寬帶混沌信號的最佳參數(shù)空間。
[Abstract]:Chaotic optical signals based on semiconductor lasers have been widely used in chaotic secure communication, chaotic radar, the generation of true random numbers and time domain reflectors. Generally, semiconductor lasers obtain chaotic signals by introducing external disturbances such as optical feedback, optoelectronic feedback, optical injection and current modulation. Because of its simple structure, easy integration, low cost and easy control, optical feedback is the main method to generate chaotic optical signals. However, the bandwidth of chaotic signals based on optical feedback is usually only a few GHz and has obvious delay characteristic (TDS). This not only limits the information transmission rate of chaotic secure communication, but also greatly reduces the security of system communication. Therefore, it is of great significance to study the theory and technology of obtaining wideband chaotic signals obviously suppressed by TDS. In this paper, a method of obtaining wideband chaotic signal of TDS is presented by using the high nonlinear fiber loop mirror (HNFLM) which is composed of high nonlinear fiber (HNLF) and fiber coupler (FC). Using the method of standard bandwidth and autocorrelation function (ACF), the influence of HNFLM on the bandwidth of chaotic signal and the influence of TDS on the chaotic signal of distributed feedback semiconductor laser (DFB-SL) under optical feedback are studied theoretically. The results show that when the chaotic optical signal generated by optical feedback DFB-SL passes through a HNFLM composed of a FC with a power fraction of 7:3 (PSR) and a HNLF with a length of 35m, The bandwidth of chaotic signal is increased from 12. 3 GHz to 41. 2 GHz, and the maximum 蟽 of ACF of its time series is reduced from 0. 22 to 0. 05. The enhancement of chaotic signal bandwidth and the effect of TDS suppression are related to the average power of the incident chaotic signal, the high nonlinear fiber length and the PSR of the fiber coupler. Among them, the delay characteristic of chaotic signal is mainly influenced by PSR. In addition, when the PSR of the fiber coupler is 7:3, the distribution of the chaotic signal bandwidth and the TDS in the parameter space composed of the average power of the chaotic signal and the length of the high nonlinear fiber are plotted. The optimal parameter space for obtaining wideband chaotic signals with low TDS using high nonlinear fiber loop mirror is determined.
【學位授予單位】：西南大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TN248.4

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