【作者】 董丽丽；

【导师】 唐文彦； 许文海；

【作者基本信息】 哈尔滨工业大学 ， 仪器科学与技术， 2008， 博士

【摘要】 近些年,大功率半导体激光器阵列(High-power Laser Diode Arrays-HLDA)作为固体激光器泵浦光源或直接光源在工业、军事等领域中得到越来越广泛的应用。目前,对于HLDA的研究主要集中在两方面:一是以提高输出功率为目的的结构设计、热特性分析、封装技术研究等;二是HLDA光束整形、耦合系统设计。对于它的远场分布、束宽、发散角等光束特性的研究却比较少,而这些特性对于HLDA光束质量评价及其光束整形系统设计具有重要意义。本文以研究HLDA的光束特性及其测试技术为主要目的,主要研究内容有:在查阅大量文献资料的基础上,综述了目前有关半导体激光器光束特性的研究现状,并分析了当前的方法和技术应用于HLDA光束特性研究时存在的问题。针对这些问题,文中首先基于亥姆霍兹方程和单管半导体激光器的远场分布特性,建立了HLDA的远场分布模型。并以不同类型的HLDA为测试对象,验证了模型的正确性。利用该模型在已知HLDA结构参数的基础上能够有效地分析其传输特性。以该模型为基础结合实验分析了HLDA的远场光强分布特性,并进一步分析了驱动电流、bar不发光等重要因素和现象对光强分布的影响,得出:在光束传输到一定距离后,HLDA的远场光强分布在平行于PN结方向上呈双峰结构,且驱动电流、bar不发光等不会改变这一双峰结构特性。针对当前束宽定义在实际应用中存在的问题,提出了一种束宽求解新方法。该方法以光斑边缘曲线的几何特征为基础求解光束束宽,光斑边缘曲线利用改进的高斯滤波器结合光强的梯度变化来检测求解。通过实验对比证明利用改进的高斯滤波器能够获得较好的光斑边缘检测结果。根据对HLDA束宽特性的分析可知在HLDA的光强分布没有形成双峰结构前,光束在垂直PN结和平行PN结方向上的束宽(ωx和ωy)随传输距离呈非线性变化;当HLDA光强分布成固定的双峰结构后,ωx、ωy随传输距离呈线性变化。这一结论对于HLDA发散角测试方法和测试系统的研究具有重要作用。针对HLDA的面发光特性,提出了基于双光斑外缘曲线的HLDA发散角计算方法,并设计了相应的光接收探测装置。探测装置由两个同心,但半径大小不同的半圆环探头组成,测试时,两个半圆环探头分别探测获得光束在两个不同传输距离处的光斑边缘曲线。与传统方法相比,使用该方法测试HLDA发散角更为合理,误差更小。该方法的提出和测试装置的设计解决了当前HLDA发散角测试时存在的两个主要问题:一是消除了把HLDA的面发光当作点光源处理所引起的测量误差;二是避免了由于HLDA输出功率过高而损坏或烧毁探测器。基于文中提出的束宽和发散角的计算原理,设计研制了HLDA光束特性测试系统,利用该系统可以测试HLDA的光强分布特性、束宽特性和发散角特性。为提高测试精度,对系统主要误差来源进行分析,并根据各种误差的特点,分别采取了多次测量取平均、对心调解、光强补偿等方法来减小测量误差。通过与标准仪器比对可知该系统的束宽测量相对误差小于5%,发散角测量误差小于0.5°。更多还原

【Abstract】 In recent years High-power Laser Diode Arrays-HLDA has been used widely in the industrial, military fields as pumping source of solid-state lasers or direct light source. At present, study on HLDA is mainly focused on two aspects. One aspect of studies includes structure design, thermal analysis, packaging techniques, these studies could improved output power development of HLDA. The other aspect is the beam shaping system design. But the beam characteristics of HLDA such as far-field distribution, beam width and divergence angle are rarely studied. These characteristics are crucial for the evaluation of HLDA beam quality and design of shaping system. This dissertation mainly studies the beam characteristics and testing technology of HLDA are studied. The main research contents of the papers are as follows:The paper summarizes the current beam characteristics development, and analyzes existent problems of current methods and techniques for HLDA. In order to solve these problems, based on Helmholtz equation and far-field distribution characteristics of single laser diode(SLD), a far-field expression of HLDA is established firstly in the paper. The different HLDAs are used to verify the expression. If the structure parameters of HLDA are known, its’transmission characteristics can be analyzed by the far-field expression. A conclusion is given on the base of theoretical analysis and the experiment results, which is HLDA’s far-field intensity distribution has the bi-peak structure paralleling to PN out of the certain propagation distance. And the bi-peak structure parallel to PN can’t been changed by driving current and the non-luminescence bars.In order to solve the problem of beamwidth definition in the practical application, a new method of the beamwidth solution is proposed. In the method, the facula edge points and edge curve are solved for the beamwidth solution based on improved Gaussian filter and intensity grads. The contrast experiments show that facula edge points and edge curve can be detected accurately by improved Gaussian filter. By the analysis of the beam width property of HLDA,a conclusion can been drew that the change ofωx andωy is non-linear by the change of the propagation distance before the formation of bi-peak structure of HLDA’s intensity distribution and the change ofωx andωy is linear by the change of the propagation distance after the formation of bi-peak structure. The conclusion plays very important role in the research of method and system of divergence angle testing of HLDA.Aiming at the plane- luminescence characteristic of HLDA, the testing method of divergence angle using the double-facula edge curve is presented. And the device of receiving and detecting light is designed. The device is made of two hemi-toroidal probes. Two probes can detect two facula edge curves on different transmission distance. By the contrast analysis for the calculating results, the divergence angle is more reasonable and has smaller error by the double-faculas edge curve method than other methods. Two key problems discovered in the present divergence angle testing are resolved by the method and the device. One is testing error induced looking HLDA as point light source is eliminated. The other problem that HLDA is destroyed or burned because of high power is resolved.On the base of aforesaid calculation principle of beamwidth and divergence angle, the testing system of HLDA’s beam characteristics is designed and implemented. The system can test the far-field intensity distribution, beamwidth and divergence angle. In order to improve measuring accuracy, the main sources of systematic error are analyzed. And in the system there are many methods used to reduce error such as taking mean, centering adjustment and intensity error compensation. Intercomparison results with standard instrument shows that measuring relative error of beamwidth is less than 5% and measuring error of divergence angle is less than 0.5°.更多还原