本文選題：光纖激光器 + 頻域動(dòng)力學(xué)��； 參考：《國(guó)防科學(xué)技術(shù)大學(xué)》2015年博士論文

【摘要】：論文針對(duì)光纖環(huán)形激光器(FRL)在工程應(yīng)用中出現(xiàn)的復(fù)雜多模動(dòng)態(tài)現(xiàn)象,通過改進(jìn)多通道實(shí)時(shí)頻域觀測(cè)手段,突破傳統(tǒng)激光動(dòng)力學(xué)測(cè)量技術(shù)的頻域限制,將人們對(duì)FRL非線性動(dòng)力學(xué)特性的認(rèn)識(shí)從低維拓展至高維,揭示了模式個(gè)體行為與集群行為之間的復(fù)雜關(guān)聯(lián)及內(nèi)在物理機(jī)制。激光頻域動(dòng)力學(xué)問題是光學(xué)復(fù)雜系統(tǒng)研究領(lǐng)域的一大難題。FRL是典型的大自由度光學(xué)復(fù)雜系統(tǒng),具有復(fù)雜跳模、高維混沌等非線性模式動(dòng)態(tài)行為�，F(xiàn)有的理論模型及測(cè)量手段大多只關(guān)注密集模式群落的整體行為,而忽視了模式個(gè)體行為;這一降維處理方式丟失了大量的頻域模式動(dòng)態(tài)信息,導(dǎo)致跳模抑制、高維頻域混沌產(chǎn)生及控制等頻域非線性動(dòng)力學(xué)問題無法得到有效處理。要解決這些問題,需在理論上建立包含密集縱模間相互作用與耦合機(jī)制的物理模型,更需發(fā)展多模激光模式動(dòng)態(tài)行為測(cè)量的實(shí)驗(yàn)手段。論文以摻鉺光纖環(huán)形激光器(EDFRL)作為研究對(duì)象,通過引入密集縱模間的交叉耦合系數(shù),并考慮鉺離子對(duì)猝滅效應(yīng)而引入額外自由度,建立了雙模及多模光纖激光頻域動(dòng)力學(xué)模型,可有效描述頻域內(nèi)大量模式的個(gè)體行為及集群行為,在理論上重現(xiàn)了頻域高維動(dòng)力系統(tǒng)所特有的多模動(dòng)態(tài)特性。仿真結(jié)果表明,通過改變離子對(duì)濃度或抽運(yùn)系數(shù),所有模式可通過陣發(fā)、倍周期分岔、準(zhǔn)周期等途徑同步進(jìn)入混沌,關(guān)聯(lián)維數(shù)高達(dá)5.1。為實(shí)驗(yàn)獲取光纖激光多模動(dòng)態(tài)信息,提出一種基于光學(xué)外差和時(shí)頻分析技術(shù)(OH-JTFA)的頻域動(dòng)態(tài)測(cè)量方法,實(shí)現(xiàn)了EDFRL密集模式頻率及強(qiáng)度多參量時(shí)間序列的同步提取,頻率分辨率在kHz量級(jí)。分別考察了單FBG選模EDFRL、自組織反饋EDFRL、調(diào)制型混沌EDFRL等三類光纖激光系統(tǒng)的頻域動(dòng)態(tài)特性,以揭示模式個(gè)體行為與群體行為間的復(fù)雜互動(dòng)及演化規(guī)律。單FBG選模EDFRL常被認(rèn)為是最典型的單波長(zhǎng)激光系統(tǒng),實(shí)際上在選模通道內(nèi)寄居上百個(gè)本征模式,自由運(yùn)轉(zhuǎn)條件下輸出非穩(wěn)態(tài)多縱模(MLM)。通過采用OH-JTFA方法,首次清晰測(cè)得該類EDFRL輸出密集多模呈現(xiàn)的豐富局域動(dòng)態(tài)現(xiàn)象,發(fā)現(xiàn)模式群落整體行為處于光強(qiáng)穩(wěn)態(tài)時(shí),模式個(gè)體行為可呈現(xiàn)典型的混沌特征。自組織反饋EDFRL在腔內(nèi)引入飽和吸收體形成超窄帶自適應(yīng)光柵,理論上可始終保持單縱模(SLM)穩(wěn)定輸出。然而,真實(shí)激光器存在多類型的跳�，F(xiàn)象,受限于常規(guī)跳模檢測(cè)手段,而無法有效獲取跳模全過程的關(guān)鍵信息。通過采用OH-JTFA方法,實(shí)現(xiàn)了對(duì)跳模全動(dòng)態(tài)過程的實(shí)時(shí)監(jiān)測(cè),跳模過程由時(shí)頻瀑布圖直觀呈現(xiàn),首次無失真地獲取到跳模瞬態(tài)過程的所有物理參量。調(diào)制型混沌EDFRL通過引入一個(gè)自由度,使總光強(qiáng)呈混沌輸出,是典型的低維混沌系統(tǒng)。同樣,該系統(tǒng)輸出光場(chǎng)包含大量密集縱模,當(dāng)總光強(qiáng)輸出為混沌態(tài)時(shí)頻域內(nèi)各模式動(dòng)態(tài)特性及演化規(guī)律迄今仍不清楚。通過提高OH-JTFA的頻域分辨率,同步提取出單個(gè)模式頻率、譜線及光強(qiáng)等多參量時(shí)間演化特性;發(fā)現(xiàn)當(dāng)總光強(qiáng)為低維混沌輸出時(shí),單個(gè)模式在頻域上出現(xiàn)頻率調(diào)制及譜線加寬現(xiàn)象、在強(qiáng)度上呈現(xiàn)高維混沌或隨機(jī)特征。論文中得到的重要實(shí)驗(yàn)結(jié)果及創(chuàng)新點(diǎn)主要包括以下三個(gè)方面:1、通過OH-JTFA方法在單FBG MLM-EDFRL中發(fā)現(xiàn)了一類大自由度非線性動(dòng)力系統(tǒng)所特有的動(dòng)態(tài)現(xiàn)象。測(cè)量結(jié)果表明,局域模式產(chǎn)生了總光強(qiáng)所無法呈現(xiàn)的頻域動(dòng)態(tài)行為,包括模式自脈沖、模式反相動(dòng)態(tài)、混沌多模振蕩、隨機(jī)多模振蕩等。2、利用OH-JTFA方法首次獲得了自組織反饋SLM-EDFRL典型跳模及瞬時(shí)多模振蕩演化過程的時(shí)頻瀑布圖。本方法是迄今唯一能實(shí)現(xiàn)同步提取EDFRL跳模持續(xù)時(shí)間、跳模間距與方向、參與競(jìng)爭(zhēng)的模式數(shù)量、模式強(qiáng)度演化等跳模參數(shù)的頻域測(cè)量手段,為深入理解模式失穩(wěn)及動(dòng)態(tài)機(jī)理提供了更全面的觀測(cè)手段,具有重要的參考價(jià)值。3、通過提高OH-JTFA的頻域分辨率,考察了抽運(yùn)調(diào)制型混沌光纖激光系統(tǒng)的頻域動(dòng)力學(xué)特性,發(fā)現(xiàn)了總光強(qiáng)表現(xiàn)為典型的低維混沌時(shí),頻域內(nèi)存在的大量縱模表現(xiàn)出極為復(fù)雜的高維動(dòng)態(tài)特性。對(duì)各模式進(jìn)行的非線性時(shí)間序列分析表明具有混沌特性的模式與具有隨機(jī)演化特性的模式在總的低維混沌下共存。在此基礎(chǔ)上,進(jìn)一步探討了利用混沌光纖激光器頻域內(nèi)的大量混沌/隨機(jī)模式作為光子熵源來生成多通道物理隨機(jī)碼的可行性。
[Abstract]:In this paper, the complex multimode dynamic phenomenon of fiber ring laser (FRL) is used in the engineering application. By improving the multi-channel real-time frequency domain observation method, the frequency domain limitation of the traditional laser dynamic measurement technology is broken through. The understanding of the nonlinear dynamic characteristics of the FRL is extended from low dimension to high dimension, and the individual behavior and set of the model is revealed. The complex association and internal physical mechanism between group behavior. The problem of laser frequency domain dynamics is a major problem in the field of optical complex systems..FRL is a typical large degree of freedom optical complex system with complex dynamic behavior such as complex mode jumping, high dimensional chaos and so on. Most of the existing theoretical models and measurement means are mostly focused on the intensive mode. The whole behavior of the community is ignored, and the pattern individual behavior is ignored. This way of reducing the dimensional dynamic information in frequency domain, which leads to the suppression of die hopping, and the nonlinear dynamic problems in frequency domain, such as high dimensional frequency domain chaos generation and control, can not be effectively dealt with. The physical model of interaction and coupling mechanism needs to develop the experimental means of dynamic behavior measurement in multimode laser mode. The paper uses an erbium doped fiber ring laser (EDFRL) as the research object. By introducing the cross coupling coefficient between the dense longitudinal modes and introducing the additional degree of freedom for the quenching effect of Erbium ion, the two mode and multi modes are established. The frequency domain dynamic model of the optical fiber laser can effectively describe the individual behavior and cluster behavior of a large number of modes in the frequency domain. In theory, the multimode dynamic characteristics peculiar to the high dimensional power system in the frequency domain are reproduced. The simulation results show that by changing the ion pair concentration or pumping coefficient, all patterns can pass through the formation, the period doubling bifurcation, the quasi periodic and so on. The path synchronization enters chaos, and the correlation dimension is up to 5.1. to obtain the multi mode dynamic information of optical fiber laser. A frequency domain dynamic measurement method based on optical heterodyne and time-frequency analysis technology (OH-JTFA) is proposed. The synchronous extraction of multi parameter time series of frequency and intensity in EDFRL intensive mode is realized. The frequency resolution is in the order of kHz. Single FBG mode selection EDFRL, self organizing feedback EDFRL, modulated chaotic EDFRL and other three kinds of optical fiber laser systems are dynamic in frequency domain to reveal the complex interaction and evolution law between mode individual behavior and group behavior. The single FBG mode selection EDFRL is often considered as the most typical single wavelength laser system, and in fact resides hundreds of eigenvalues in the mode selection channel. In the mode, the unsteady multi longitudinal mode (MLM) is output under free running condition. By using the OH-JTFA method, the rich local dynamic phenomenon of the EDFRL output dense multimode is clearly detected for the first time. It is found that the pattern community's behavior can show the typical chaotic characteristics when the whole behavior of the pattern community is in the light steady state. The self organizing feedback EDFRL is introduced in the cavity. The saturated absorber forms a super narrow band adaptive grating, which can always maintain the stable output of the single longitudinal mode (SLM) in theory. However, there are many types of die jumping phenomenon in the real laser, which is limited by the conventional mode hopping method, but can not effectively obtain the key information of the whole process of the die hopping. Through the OH-JTFA method, the full dynamic process of the die hopping is realized. In real time monitoring, the hopping process is presented directly by the time frequency waterfall graph, and all physical parameters of the transient process are obtained without distortion for the first time. The modulated chaotic EDFRL is a typical low dimensional chaotic system by introducing a degree of freedom to make the total light intensity chaotic output, and the output light field of the system contains a large number of dense longitudinal modes, when the total intensity of light is strong. The dynamic characteristics and evolution laws of each mode in the frequency domain are still unclear. By improving the resolution of the frequency domain of OH-JTFA, the time evolution characteristics of multiple parameters, such as single mode frequency, spectral line and light intensity, are extracted synchronously. It is found that when the total light intensity is low dimensional chaotic output, the frequency modulation and spectral lines appear in the frequency domain by a single mode. The important experimental results and innovation points in this paper mainly include the following three aspects: 1, the dynamic phenomena of a class of large degree of freedom nonlinear dynamical systems are found in a single FBG MLM-EDFRL by OH-JTFA method. The results show that the local mode produces the total. The frequency domain dynamic behavior that the light intensity can not present, including the mode self pulse, the pattern inverse phase dynamics, the chaotic multimode oscillation, the random multimode oscillation, and so on, uses the OH-JTFA method to obtain the time frequency waterfall diagram of the self organized feedback SLM-EDFRL typical model and the transient multimode oscillation evolution process for the first time. This method is the only method to achieve the synchronous extraction of EDFRL in SLM-EDFRL. The duration of die jumping, the distance and direction of the die, the number of modes involved in the competition and the frequency domain measurement of the model strength evolution, provide a more comprehensive observation method for understanding the mode instability and dynamic mechanism, which has important reference value.3. By improving the resolution of OH-JTFA in frequency domain, the pump modulation chaos is investigated. In the frequency domain dynamics of the optical fiber laser system, it is found that when the total light intensity is characterized by a typical low dimensional chaos, a large number of longitudinal modes in the frequency domain show very complex high dimensional dynamic characteristics. The nonlinear time series analysis of the modes shows that the mode with the chaotic characteristic and the pattern with random evolution characteristics are generally low. On this basis, the feasibility of using a large number of chaotic / random modes in the frequency domain of a chaotic fiber laser as a photon entropy source to generate multi-channel physical random codes is further discussed.
【學(xué)位授予單位】：國(guó)防科學(xué)技術(shù)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：TN248

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本文編號(hào)：1929351