【作者】 曹长庆；

【导师】 曾晓东；

【作者基本信息】 西安电子科技大学 ， 光学工程， 2010， 博士

【摘要】 本文研究了半导体激光器光束特性及应用方面的若干问题。对半导体激光器光场特性的研究,有助于半导体激光器列阵光束整形和泵浦固体激光器应用。本文研究了大功率半导体激光器远场分布,分析了半导体激光器的远场误差和反源技术,还探讨了半导体激光器的光束质量评价方法,研究了异型棱镜整形技术和紧耦合泵浦技术。论文主要内容分为四部分：论文第一部分,研究了半导体激光器的远场光分布；讨论了源振幅扰动对远场分布的影响,对半导体激光器的远场误差和反源技术进行了深入分析。针对平面源,在非傍轴理论的基础上,详尽讨论了由于源振幅扰动而产生的远场误差,建立了一种恰当的描述远场误差的方法,即由“相对误差面积”、“离轴距离”和“判据点”相结合的描述方法。模拟试验表明,“离轴距离”和“判据点”是影响远场误差的重要因素。为了解半导体激光器的传播模近场分布,基于远轴光传播理论,利用远场分布的光强和逼近信赖域的局部优化方法,提出了一种新的计算传播模近场分布的方法,模拟实验表明,只需很少几个展开函数的线性组合,就能很好地逼近源场函数,是一种稳定性好,精度较高的方法。论文第二部分,探讨了用光束准直时所付出的代价来评价光束质量好坏的方法。研究结果表明：条形半导体激光器和堆积式半导体激光器列阵的输出光场随传输距离不同,远、中、近分布特性差异明显。光束质量参数(忽略"smile效应”)与单个发光点光束参数积、占空比以及发光点(或BAR条)数量密切相关。利用半导体激光器的自身参量(L,θ和As)组成的Q因子加强了参数L//、θ⊥的影响,兼顾了波长和像散因子As的影响,更能反映它们对准直难度的影响,Q因子较好地反映出光束准直的难易程度。论文第三部分,根据二维大功率半导体激光器输出光场的特点,提出一种新型堆积式半导体激光器列阵光束整形方案。该元件是棱锥形输出结构,可以压缩光束发散角和光斑尺寸。该系统具有结构简单、加工容易以及对准容差大的优点。根据器件的远场分布特征细致研究了异型棱镜的传输特性,利用光线追迹法计算了输出面的光强度分布和光束发散角,并给出棱镜参数的计算方法。通过适当选择棱镜的结构参量,可以在输出像面上得到较均匀的光斑,在这个范围内的光能量约占总辐射能量的80%,光强起伏小于5%。论文第四部分,研究了微型模块化DPL的关键技术之一——紧耦合泵浦技术的可行性。在半导体制冷器传导制冷的工作方式下,设计了双LD侧面泵浦板条Nd:YAG激光器的方案。理论分析并在室温条件下实现了连续激光输出,LD耦合效率>90%,达到了设计指标。更多还原

【Abstract】 Several key issues of semiconductor lasers are discussed in this paper. Study on the characterizations of irradiance distribution is significant for the practical applications of laser beam shaping and solid-state laser pumping. The characterizations of irradiance distribution, the far-field error and the near-field distributions of semiconductor lasers, the discussion of evaluation on beam quality of semiconductor lasers, a new beam shaping device, and the tightly coupled pumping technology are discussed in this paper. The key issues discussed in this paper are divided into four parts:In the first part of this paper, the far-field error and the near-field distributions of semiconductor lasers are studied synthetically. "Relative error volume" gave the maximum error range of the far-field error. For practical work, it is important to provide an accurate description of the far-field error in terms of the source error. The "critical point" of the far-field phase error is derived, analyzed and proposed to decide the off-center source error. Numerical results show that the off-center distance should be used in describing the source error and analyzing the far-field errors, and the "critical point" is the useful parameter in analyzing the source error for the inverse problem.Based on the far-field data, a new approaching trust region local optimization algorithm has been used to determine the near-field distribution. Numerical results demonstrate that the field distribution function of the source could be approached by a sum of some simple functions, and our method is simple and of high efficiency.In the second part of this paper, the characterizations of irradiance distribution are studied, and the discussion of evaluation on beam quality of semiconductor lasers is mainly researched. The intensity expression of laser diode bar and laser diode stacked array have been derived and illustrated with numerical examples. The intensity changed obviously with distances. Based on the beam characteristics of semiconductor lasers, a new parameter for evaluating beam quality of high power semiconductor lasers is introduced. The shortcomings of M2 factor used in evaluating beam quality of semiconductor lasers are discussed and its limitations are pointed out. Moreover, some important aspects of the beam quality factor are discussed. The main factors to influence collimating the beam of semiconductor lasers are analyzed. Our results give us grounds to make the following conclusions:the smaller the value of the new parameter is, the more easily the beam is collimated. In the third part of this paper, a new beam shaping device of diode laser stack is presented. The shaping element consists of a glass pyramid with spherical or plane output surface. The large divergence angle and the overall aperture area are compressed by this beam shaping system. The transformation characteristics are presented and the optimization performance is investigated based on the ray-tracing method. Analysis shows that high irradiance can be obtained. This beam shaping system can be easily fabricated and has large alignment tolerance.In the fourth part of this paper, tightly coupled pumping technology of micro-modularization DPL is studied. An experimental equipment of laser diode symmetrically side-pumped Nd:YAG slab laser is designed. The influence of laser diode on pump distribution of gain medium is measured and analyzed. Study shows that more diodes lead to better pumping intensity distribution; the least absorption coefficient of laser medium, the best pumping intensity distribution; the smaller distance between diode and laser medium, the worse pumping intensity distribution. The efficiency of coupling,>90%, accords with the design index.更多还原