全腔水冷辐射板条固体激光热效应及被动调Q特性研究

发布时间：2018-04-12 19:16

本文选题：全腔水冷 + 板条激光器　；参考：《哈尔滨工业大学》2015年硕士论文

【摘要】：高功率固体激光器以体积小、可靠性强、转换效率高等著称,已被广泛应用于军事、医疗、工业加工等多个领域。其中,相比较于棒状固体激光器,板条状固体激光器能够获得具有更高光束质量的光,更高的输出功率以及更高的效率,一直以来都深受人们的关注。固体激光器工作时,会有相当大的一部分泵浦光转化为热滞留在激光介质内,使其温度升高。而对激光介质的冷却,通常为外部冷却,这样将会导致介质内温度不均匀分布的现象,温度的不均分布和因其产生的热应力都将会引起一系列热效应问题。因此,对激光介质的温度及应力等的分布状况进行研究是很有必要的。本课题采用氙灯泵浦8板条辐射状激光增益介质(8个板条呈“米”字型排列),能有效增加泵浦面积和激光介质的散热面积,这样既能够有效提高激光器的转换效率又能有效减弱其热效应。同时,为了提高输出光的峰值功率,扩大激光器应用范围,本课题加入了被动调Q技术。本文主要研究的内容包括激光介质温度及热应力分布的理论分析及数值模拟,被动调Q的相关理论及实验研究,激光器聚光腔的优化设计,具体研究内容总结如下:(1)给出了本课题研究的背景、意义,总结概述了板条状固体激光器国内外研究现状,概括阐述了板条状激光介质热效应的相关问题及一些制冷方式,并对被动调Q激光器的研究概况做了简单总结。(2)简单介绍了温度场及热应力应变场的描述等问题,理论研究了辐射板条激光介质的热分析问题,并通过运用ANSYS软件对辐射状板条激光介质在不同条件下的温度及热应力分布做了有限元模拟分析,并最后给出了实况下激光介质的温度及应力分布的有限元模拟结果。(3)阐述了被动调Q的基本原理,被动调Q晶体Cr4+:YAG的基本性质、光谱特性、能级结构及可饱和吸收特性,给出了晶体Cr4+:YAG被动调Q的速率方程,并对其进行了仿真分析,最后利用速率方程对调Q激光输出特性进行相关求解和分析。(4)对辐射板条激光器的聚光腔部分进行了优化设计,实现了辐射板条激光器的自由运转。利用矩阵光学理论并借助MATLAB软件分析了光斑聚焦特性,在此基础上确定了调Q晶体的具体位置,并进行了辐射板条激光器的被动调Q实验。
[Abstract]:High power solid-state lasers are known for their small size, high reliability and high conversion efficiency. They have been widely used in military, medical, industrial processing and other fields.Compared with the rod solid state laser, the strip solid state laser can obtain higher beam quality, higher output power and higher efficiency.When the solid-state laser is working, a considerable part of the pump light will be converted into hot trapped in the laser medium, and the temperature will rise.However, the cooling of laser medium is usually external cooling, which will lead to the phenomenon of uneven distribution of temperature in the medium, and the uneven distribution of temperature and the thermal stress will cause a series of thermal effects.Therefore, it is necessary to study the temperature and stress distribution of laser medium.In this paper, the Xenon lamp is used to pump 8 strip radiative laser gain media (8 strips are arranged in "meters" shape), which can effectively increase the pump area and the heat dissipation area of the laser medium.In this way, the conversion efficiency of the laser can be improved and the thermal effect can be weakened effectively.At the same time, in order to increase the peak power of output light and expand the application range of laser, passive Q-switched technology is added in this paper.The main contents of this paper include the theoretical analysis and numerical simulation of the temperature and thermal stress distribution of laser medium, the theoretical and experimental study of passive Q-switching, the optimization design of laser condenser.The specific research contents are summarized as follows: (1) the background and significance of the research are given, the research status of plate solid state laser at home and abroad is summarized, and the related problems and some refrigeration methods of the thermal effect of strip laser medium are summarized.A brief summary of the research of passive Q-switched laser is given. The description of temperature field and thermal stress-strain field is briefly introduced, and the thermal analysis of radiation slab laser medium is studied theoretically.By using ANSYS software, the temperature and thermal stress distribution of radiative lath laser medium under different conditions are simulated and analyzed by finite element method.Finally, the finite element simulation results of temperature and stress distribution of laser medium are given. The basic principle of passive Q-switched crystal Cr4: YAG is described. The basic properties, spectral characteristics, energy level structure and saturable absorption characteristics of passively Q-switched crystal Cr4: YAG are described.The rate equation of passively Q-switched crystal Cr4: YAG is given and simulated. Finally, the output characteristics of Q-switched laser are solved and analyzed by using the rate equation.The free operation of the radiation lath laser is realized.Based on matrix optics theory and MATLAB software, the spot focusing characteristics are analyzed, and the specific position of Q-switched crystal is determined, and the passive Q-switching experiment of the radiation slab laser is carried out.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN248.1

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