增益与损耗控制下输出高阶拉盖尔与贝塞尔高斯光束端泵激光器研究

发布时间：2018-03-16 04:36

本文选题：端面泵浦固体激光器　切入点：高阶拉盖尔高斯光束　出处：《华中科技大学》2016年博士论文　论文类型：学位论文

【摘要】：随着光学应用在各个领域的不断深入,高阶拉盖尔高斯(Laguerre Gaussian, LG)光束与高阶贝塞尔高斯(Bessel Gaussian, BG)光束由于其独特的光学特性在近二十年来逐步引起了人们的广泛关注,不仅应用到光镊、超材料激光加工、荧光受激损耗发射技术、自由空间光通信等经典领域,还深入到量子纠缠和量子通信等领域。而研究高阶LG光束和BG光束的基础和关键之一在于如何获得模式纯度高的光束。输出高阶LG光束与BG光束的端面泵浦固体激光器因其全固态、效率高、输出光束功率高、光束模式纯度高、结构紧凑、稳定性高等优点,得到了持久和深入的研究。本论文基于激光谐振腔中增益与损耗控制的横模选择技术,对输出高阶LG光束和BG光束端面泵浦固体激光器进行了深入的研究。论文首先介绍了高阶LG光束和BG光束在各领域中的应用,分析了各种高阶光束的产生方法,并综合输出高阶LG光束和BG光束的端面泵浦固体激光器的国内外研究进展,提出了基于增益与损耗控制的输出高阶LG光束和BG光束端面泵浦固体激光器的思路。本论文的主要研究内容由以下几部分组成：基于激光谐振腔横模选择技术中的增益控制的原理,提出了一种环形光束端面泵浦固体激光器结构,实验上实现了涡旋拉盖尔高斯(vortex Laguerre Gaussian, vLG)光束的连续和脉冲输出。设计了一种环形泵浦光形成的装置和方法,分别从光线追迹和衍射积分角度,分析了该装置的实现原理与输出光束光学特性,并进行了实验验证。基于增益控制的原理,采用该装置形成的环形光束端面泵浦a切Nd:YVO4晶体,搭建了固体激光器,实现了最大输出功率574mW的vLG0,1光束连续输出。输出光束的轨道角动量特性由马赫增德尔干涉仪来检测：并在该连续工作的激光器中插入被动调Q晶体Cr4+:YAG后,实现了重复频率65KHz,脉宽198ns的脉冲vLG光束输出。提出了环形光束端面泵浦下圆棒激光晶体的热效应模型。从一维热传导方程出发,将环形光束等效为半径方向上离轴高斯光束,理论推导了圆棒激光晶体在环形光束端面泵浦下的温度分布、热致相位差分布、等效热焦距和热致损耗。以1.3%掺杂的Nd:YAG圆棒激光晶体为例,模拟分析了激光晶体内温度、热致光程差、等效热焦距和热致损耗随着环形泵浦光尺寸的变化规律。模拟结果表明,在相同泵浦功率下,相对于实心光束泵浦,环形泵浦下,晶体中心部分的温度升高明显降低,这对于提高泵浦效率提供了有利保障；模拟结果还表明,相对于环形泵浦光的厚度,环形泵浦光的光强最强中心位置更加影响激光晶体的热分布。基于平凹谐振腔中横模选择技术的损耗控制原理,提出了一种基于损耗控制的高阶LG光束输出的激光器结构。从高阶LG光束的光强空间分布特性出发,在光强节线分布位置,通过插入振幅模板,利用振幅模板对于各个高阶LG光束的透过率不同,达到增大包括基模在内其它模式损耗的目的。采用有源谐振腔的模拟方法,分别模拟了径向高阶LG光束、角向高阶LG光束和常规高阶LG光束的选择激发和输出。模拟结果表明该谐振腔结构输出的高阶LG光束的模式纯度均超过93%。并分析了插入振幅模板的端面泵浦有源谐振腔内损耗分布,建立了该激光器的损耗分布模型。最后,采用修正的马赫-曾德尔干涉仪对腔外高阶LG转换成高阶vLG光束的方法进行了探讨。基于轴棱锥谐振腔中横模选择技术的损耗控制原理,提出了一种基于损耗控制的叠加态的高阶BG光束输出的激光器结构。研究了轴棱锥谐振腔中振荡高阶BG光束的模式特性,指出了其振荡的模式是两个涡旋方向相反的高阶BG光束的叠加。利用损耗控制的方法,在谐振腔中放置振幅模板,利用振幅模板对于各个高阶BG光束的透过率不同,增大目标模式以外其它模式的损耗。采用有源谐振腔的模拟方法,模拟了叠加态高阶BG光束的输出。并对该激光器模拟输出光束的自由空间传输特性和角谱特性进行了研究,模拟结果表明该激光器输出光束具有无衍射特性,具备高阶BG光束的特性。同时,采用轨道角动量谱分析方法对其模式组成进行了分析,结果表明轴棱锥谐振腔中振荡的高阶光束是叠加态的高阶BG光束。
[Abstract]:With the development of optical applications in various fields, high order La Gail Goss (Laguerre Gaussian, LG) beam with high order Beisel Goss (Bessel Gaussian, BG) beam due to its unique optical properties gradually aroused people's attention in the past twenty years, not only to the application of optical tweezers, ultra laser processing of materials, by fluorescence the loss of excitation emission technology, free space optical communication and other classical field, but also deep into the quantum entanglement and quantum communication and other fields. And the study of high order LG beam and BG beam is one of the foundation and the key is how to obtain the high purity of the beam mode. The end pumped solid state laser output of high order LG beam and BG beam because of its solid state, high efficiency, high power output beam, beam mode of high purity, compact structure, high stability and other advantages, has been sustained and in-depth study. This thesis is based on the gain and loss of control of laser resonator The transverse mode selection technique, the output of high order LG beam and BG beam end pumped solid-state laser is studied. The paper firstly introduces the application of high order LG beam and BG beam in various fields, analyzes the producing methods of various high order beam, research progress of end pumped solid-state lasers and high output order LG beam and BG beam at home and abroad, put forward the gain and loss of control output of high order LG beam and BG beam end pumped solid-state laser based on the idea. The main research contents of this paper consists of the following parts: the principle of laser resonant cavity transverse mode selection technology based gain control, put forward an annular beam pumped solid-state laser structure, carry out experiments on vortex La Gail Goss (vortex Laguerre Gaussian, vLG) continuous and pulse output beam. The design of an annular pump form A device and a method for tracing and diffraction integral respectively from the angle of light, analyzes the implementation principle and the output beam optical characteristics of the device, and verified by experiments. The principle of gain control based on annular beam pumped form using the device a cut Nd:YVO4 crystal, build a solid laser beam to achieve the vLG0,1 the maximum output power of 574mW continuous output. The output of the orbital angular momentum of light characteristics by Machka Del interferometer to detect and insert passively Q crystal Cr4+ laser in the continuous work: YAG, the 65KHz repetition rate, pulse width 198ns vLG output beam. The thermal effect of laser crystal with circular ring rod model the beam end pumped down. Starting from the one-dimensional heat conduction equation, the annular beam is equivalent to the radius direction of off-axis Gauss beam, deduced the rod laser crystal in the annular beam end The temperature distribution of surface pumped by thermally induced phase difference, distribution, loss and heat. The equivalent thermal focal length with 1.3% doped Nd:YAG rod laser crystal as an example, simulation analysis of the temperature of laser crystal, thermal optical path difference, the equivalent thermal focal length and thermally induced losses with varying ring pump size simulation. The results show that under the same pumping power, compared with a solid beam pump, annular pump, the central part of the crystal temperature decreased obviously, which for providing favorable protection to improve the pumping efficiency; the simulation results also show that relative to the annular pump thickness, more light intensity was the strongest central position of the ring-shaped pump heat distribution in the laser crystal plano concave resonator. In the transverse mode selection technology based on the principle of loss control, proposed a laser structure of high order LG output beam loss control based on light intensity. From the high order space LG beam points Fabric characteristics, distribution of light intensity in the pitch line, by inserting the amplitude mask, using amplitude template for each high order LG beam through the different rate of increase, including the fundamental mode, other modes of loss. The simulation method of active resonator, respectively to simulate the radial high order LG beam, the angle to the higher order LG beam and conventional high order LG beam excitation and output. The simulation results show that the high order mode purity LG beam output of the resonant cavity structure of more than 93%. and the analysis of the distribution of end pumped active resonant cavity loss into amplitude template, a loss distribution model of the laser. Finally, using the modified Maher had Del interferometer outside the cavity of high order LG into high order vLG beams are discussed. The axicon resonator transverse mode selection technology based on the principle of loss control, propose a method based on loss control The laser structure of high order BG output beam superposition system. Research on mode characteristics of the axicon in the resonant cavity oscillation of high order BG beam, the oscillation mode is the two scroll in the opposite direction of high order BG beam superposition. Using the method of loss of control, the amplitude of the template in place in the resonant cavity for each template, using the amplitude of high order BG light transmittance of different loss increases other than the target mode mode. Using simulation method of active resonator, simulate the output of superposition of higher-order BG beams. And the free space propagation characteristics and the angle of the laser beam simulation output spectrum is studied, simulation the results show that the laser beam has no diffraction characteristics, has the characteristics of high order BG beam. At the same time, the orbital angular momentum spectrum analysis method on the model were analyzed, results show that the axicon resonant cavity The high order beam of the medium oscillation is the high order BG beam of the superposition state.

【学位授予单位】：华中科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN248

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