光注入及光电反馈垂直腔面发射激光器的非线性动力学特性研究

发布时间：2018-01-09 21:47

本文关键词：光注入及光电反馈垂直腔面发射激光器的非线性动力学特性研究　出处：《西南大学》2017年博士论文　论文类型：学位论文

【摘要】：垂直腔面发射激光器(Vertical-cavity surface-emitting laser,VCSEL)是一种垂直表面发光的新型半导体激光器,结构和制作工艺的不同导致VCSEL具有阈值电流低、光纤耦合效率高、动态单纵模工作、制作成本低廉以及易于集成高密度二维阵列等独特的优势,其有望在光通信、光信息处理、并行光互连等重要应用领域取代常规的边发射型半导体激光器(Edge-emitting laser,EEL)。近年来的研究表明,在合适的光扰动或电扰动下,VCSEL可以呈现出周期性脉冲、锁频、倍周期脉冲以及混沌脉冲等丰富多样的非线性动力学态;并且,VCSEL有源区对称的结构和增益介质弱的各向异性使其输出的偏振特性非常复杂,外部的光扰动或电扰动会导致VCSEL出现偏振转换(Polarization switching,PS)和偏振双稳(Polarization bistability,PB)这两种特殊的偏振动力学状态。当前,围绕这些偏振动力学特性的研究不仅为VCSEL在全光开关、全光存储以及全光信息转换等相关技术领域的应用开辟了新的途径,而且对理解这些系统中非线性动力学态的产生和演化规律以及改善基于此类激光器器件的系统性能都具有非常重要的现实意义。基于此,本论文对VCSEL在光注入及光电反馈条件下的非线性动力学和偏振特性开展了理论和实验的研究,旨在深入剖析不同扰动环境下VCSEL系统所呈现的各类静态和动态特性,揭示这些复杂现象的外在表现形式和内在物理机制,并探寻VCSEL产生的非线性动力学、PS和PB的控制措施。主要研究内容及结论如下:1.基于VCSEL自旋反转模型,数值分析了正交光注入下VCSEL的非线性动力学特性。揭示了VCSEL两个正交偏振模式的非线性动力学态在不同注入条件下的产生及演化规律,确定了激光器在注入参数空间内的非线性动力学状态分布。数值模拟分析表明,激光器在合适的注入条件下可呈现强度诱导的PS效应,并且发生PS的参数区域往往伴随着两个模式之间的竞争或耦合。在注入参数空间内,不同偏置电流情况下VCSEL出现PS效应时所需的注入强度及输出动力学态特性均存在较大差异,系统可以通过合理地调节偏置电流、注入强度以及频率失谐等参量来有效控制VCSEL输出的非线性动力学状态。此外,提出了一种基于混沌光注入的主副VCSELs混沌系统,并对该系统产生混沌信号的带宽和复杂性演化进行数值分析。理论的分析表明,在正负频率失谐较大的区域,较大的注入强度有助于提高系统输出的两个偏振模式的混沌带宽;适当的反馈和注入条件可使系统输出混沌信号的复杂度显著提高,且其与宽带宽的混沌参数区域具有较大重合,在该参数重合区域,系统可输出具有宽带宽、高复杂度的混沌信号。2.理论研究了正交光注入1550 nm-VCSEL中强度诱导PS和PB产生的物理机理及其演化规律。结果表明,vcsel所呈现的偏振特性都与注入强度变化的路径紧密相关,系统在特定参数条件下可产生两种不同类型的强度诱导的pb效应。通过研究vcsel两个正交偏振模式沿不同注入路径时的非线性动力学状态的变化,揭示了系统在不同频率失谐情况下正/反向ps以及对应pb的变化规律。进一步的研究还表明,在偏置电流较小时,系统仅在较大的频率失谐区域出现pb效应,其宽度在正负失谐区呈现不同的变化趋势;而当偏置电流较大时,系统在较大失谐区域的pb宽度的变化与小电流情形类似,但在较小失谐区域,系统可产生无反向偏振开关的pb现象。根据系统产生pb的物理条件,详细分析了偏置电流和频率失谐参量空间内出现两类pb效应的分布情况。另外,考虑到可变偏振光注入具有更为丰富和灵活的扰动特点,搭建了可变偏振光注入1550nm-vcsel的实验系统,充分研究了注入光偏振角对强度及频率诱导pb特性的影响。研究表明,系统在特定的注入参数条件下存在着强度诱导pb效应的临界注入光偏振角,且此临界角度随频率失谐的增加而增大,在适当的参数范围内,更小的注入光偏振角度和更大的注入电流均有助于增加pb宽度;对于频率诱导的pb现象,注入光偏振角的变化对pb宽度也有着较大的影响。此外,通过正向及反向扫描注入光偏振角,可观察到偏振角度诱导的pb效应,对应的pb宽度与注入强度、频率失谐以及偏置电流均密切相关。通过合理选择注入光偏振角度和其它可控参量,系统可实现对不同类型pb的灵活调控。3.搭建了光电负反馈1550nm-vcsel的实验系统,对系统输出的非线性动力学特性进行了研究。研究发现光电反馈强度及偏置电流都会对系统输出的动态特性产生显著影响。在不同参数条件下,光电负反馈1550nm-vcsel可呈现规则脉冲态、准周期态、混沌脉冲态等丰富的非线性动力学行为。通过测定偏置电流和光电反馈强度参量空间内的动力学分布,可以发现激光器在较小偏置电流和弱光电反馈下主要工作在稳定状态,随着偏置电流的增加,激光器的输出通常会随反馈强度的增加以规则脉冲态-准周期态-规则脉冲态的方式循环演化,直到系统能够进入混沌状态;当偏置电流增加到一定值后,激光器输出的动力学态随反馈强度的增加则主要以规则脉冲态-准周期态-混沌脉冲态的方式循环演化。多种外部扰动下,vcsel的非线性动力学状态会更加丰富,其在参数空间范围可产生不同于单扰动时的动态特征分布,如何实现动力学行为的有效控制成为该类器件能否实际应用的关键。基于此,我们实验研究光电负反馈和正交光注入共同扰动下1550nm-vcsel的非线性动力学特性,发现混合扰动增加了系统的自由度,使vcsel输出的非线性动力学态相比于单一注入情况有更为复杂的变化规律。对于确定的注入条件,光电反馈强度的增加可导致系统输出准周期态和混沌态的参数区域逐渐增大,而发生单周期振荡和注入锁定的参数区域会逐渐减小,同时偏振模式发生PS时所需的注入强度也随之发生明显的变化。通过合理的调节系统扰动参量,VCSEL可实现丰富可控的非线性动力学态输出。4.基于光电负反馈1550 nm-VCSEL实验系统,详细研究了偏置电流诱导及光电反馈诱导产生的动力学态双稳的物理机理及其演化规律。分析表明,当偏置电流或光电反馈强度沿不同路径变化时,由于系统初始条件的不同,VCSEL输出的非线性动力学状态的变化规律并不完全一致,其可能在确定系统参数条件下呈现两种不同的动力学态输出行为,进而产生电流诱导或光电反馈诱导的动力学态双稳现象,此类态双稳的出现决定于VCSEL内部的非线性效应及其输出动力学状态对初始条件的高度敏感性。进一步的研究确定了电流或反馈诱导的动力学态双稳所需的参量范围,并且系统动力学态双稳的演化规律可由其输出动力学态的复杂性特征来清晰的表征。
[Abstract]:Vertical cavity surface emitting laser (Vertical-cavity surface-emitting laser, VCSEL) is a new type of semiconductor laser vertical surface emitting, structure and manufacturing process are different because VCSEL has a low threshold current, high fiber coupling efficiency, dynamic single longitudinal mode operation, low production cost and easy integration of advantages of high density two-dimensional arrays, which is expected to in optical communication, optical information processing, parallel optical interconnection and other important applications to replace the conventional edge emitting semiconductor lasers (Edge-emitting, laser, EEL). Recent studies show that in the proper light disturbance or electrical disturbance, VCSEL can exhibit periodic pulse frequency, pulse cycle times and chaotic pulse rich a variety of nonlinear dynamic state; and the anisotropic structure and gain medium VCSEL active region symmetric weak polarization characteristics make its output is very complex, external Light disturbance or electrical disturbances will lead to VCSEL (Polarization switching, PS polarization conversion) and polarization bistability (Polarization bistability, PB) of the two special polarization dynamics. At present, the research on these polarization dynamics not only for VCSEL in all-optical switching, opens a new way to application of optical storage and optical information conversion and other related technologies, and to understand the emergence and evolution of nonlinear dynamics in these systems and improve the system performance of such devices based on laser has very important practical significance. Based on this, this paper carried out theoretical and Experimental Research on VCSEL optical injection and photoelectric feedback under the condition of nonlinear dynamics and the polarization characteristics, aims to analyze the various types of static and dynamic characteristic of VCSEL system under the different disturbance, reveal the complex phenomenon The external form and internal mechanisms, and explore the nonlinear dynamics of VCSEL, control measures of PS and PB. The main research contents and conclusions are as follows: 1. based on the VCSEL model of the spin flip, the numerical analysis of nonlinear dynamic characteristics under orthogonal optical injection of VCSEL. VCSEL revealed two orthogonal polarization modes of nonlinear dynamics in the state generation and evolution of different injection conditions, laser in nonlinear dynamic state distribution parameter space injection was determined. The numerical simulations show that the laser in the appropriate injection conditions can be PS effect intensity induced, parameter area and PS is often accompanied by the competition between two modes or in injection coupling. The parameter space, the injection strength and output dynamics characteristics required for different bias current situation VCSEL PS effect when there are differences, the Department of The system can reasonably adjust the bias current, the nonlinear dynamic state injection strength and frequency detuning parameters to control the output of VCSEL. In addition, a vice principal of VCSELs chaotic system based on chaotic optical injection, and the bandwidth and complexity of chaotic signal evolution of the numerical analysis of the system. The theoretical analysis shows that in regions with large detuning, negative frequency, large injection intensity is helpful to improve the system's output of two polarization modes of the chaotic bandwidth; appropriate feedback and injection conditions can make the system output chaotic signal complexity is significantly improved, and the chaotic parameter region wide bandwidth and has a large overlap, in this parameter the overlap region, the system can output with wide bandwidth, high complexity of chaotic signal.2. theory to study the physical mechanism of orthogonal optical injection strength induced by PS and PB in nm-VCSEL and 1550 The law of evolution. The results show that the polarization properties of VCSEL presented are closely related with the path into the intensity variation of the system can produce Pb effect induced by two different types of strength under certain parameter conditions. Through the study of VCSEL two orthogonal polarization mode changes into nonlinear dynamics state along different paths when the reveals the system in different frequency detuning case positive / reverse PS and the corresponding changes in Pb. Further research showed that, in the low bias current, the system only detuning region Pb effect in a wide frequency, the width of the positive and negative detuning region showed different trend; and when the bias current is high. The system changes in a large detuning region of Pb and the width of the small current situation is similar, but smaller detuning region in Pb, the system can produce the phenomenon of no reverse polarization switching. According to the physical conditions of the Pb system, A detailed analysis of the bias current and the frequency distribution of two kinds of Pb effect in harmonic parameter space. In addition, taking into account the variable optical injection has more disturbance characteristics of rich and flexible, set up the experiment system of variable polarized 1550nm-vcsel injection, the full study of the influence of injection angle on light polarization intensity and frequency characteristics induced by Pb the system in particular. The study shows that the injection parameters exist under conditions of Pb effect critical injection intensity induced polarization angle, and increase the critical angle with the frequency detuning increasing, in the appropriate range of parameters, smaller injection light polarization angle and larger injection current are helpful to increase the width of Pb for Pb; frequency induction phenomenon, into the change of the polarization angle also has great influence on the width of the Pb. In addition, the forward and backward scanning into the polarization angle, the polarization angle can be observed by Effect of Pb mediated, and the injection strength corresponding to Pb width, frequency detuning and bias current are closely related. The polarization angle and other parameters controlled by reasonable selection of injection system can achieve flexible control of the different types of Pb.3. to build the optoelectronic negative feedback 1550nm-vcsel experimental system, the nonlinear dynamic characteristics of the system output a research found that photoelectric feedback intensity and bias current are the dynamic characteristics of the system output significantly. Under different conditions, the optoelectronic negative feedback 1550nm-vcsel can present regular pulse state, quasi periodic state, nonlinear dynamics of chaotic pulse state rich. By measuring the bias current and the intensity distribution of optoelectronic feedback dynamics the parameter space, can be found mainly in the small laser bias current and weak photoelectric feedback in the steady state, with the bias current Increase the output of the laser pulse will usually increase the evolution rules of state - quasi periodic state rules state cycles with feedback pulse intensity, until the system can enter a chaotic state; when the bias current increases to a certain value, the dynamic state of laser output with increasing the feedback intensity is mainly to state quasi regular pulse evolution periodic state to chaotic pulse state way cycle. A variety of external disturbances, nonlinear dynamic state of VCSEL will be more abundant, the parameter space can produce dynamic distribution characteristics different from the single disturbance, how to realize the effective control of the dynamic mechanical behavior of this kind of device can become the key to practical application. Based on this, we experiment study on optoelectronic feedback and optical injection of common orthogonal nonlinear perturbation of the dynamic characteristics of 1550nm-vcsel, found that the mixed disturbance increases the degree of freedom, so that the output of non VCSEL Linear dynamic state compared to the single injection is more complicated. To determine the changes of injection conditions, increase the strength of optoelectronic feedback can lead to parameters of regional system output quasi periodic and chaotic state is gradually increased, and single periodic oscillation and the injection parameters of regional lock will gradually decrease, at the same time required for polarization mode the occurrence of PS injection strength will be changed. By adjusting the system parameters perturbation, VCSEL.4. can realize the nonlinear dynamic state output rich controllable optoelectronic negative feedback 1550 nm-VCSEL experimental system based on a detailed study of the physical mechanism of bistable state dynamics and the evolution law of the bias current induced and photoelectric feedback induced. The analysis shows that when the bias current or optoelectronic feedback strength along different path changes, because of the initial condition of the system, the output of the nonlinear VCSEL Dynamics of the state is not entirely consistent, it may present two different dynamic state output parameters are determined under the condition of system behavior, and generate an electric current induced or optoelectronic feedback dynamics induced bistability, high sensitivity of such state bistability depends on the VCSEL internal nonlinear effect and dynamic state of the initial output conditions. Further research to determine the current state feedback or dynamics induced bistable parameters required for the characterization of clear evolution and system dynamic state bistability by the output dynamics of complex features.

【学位授予单位】：西南大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TN248

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