基于激光晶体热效应谐振腔的设计以及MWCNT被动调Q锁模的研究

发布时间：2018-05-16 01:33

本文选题：激光器 + 激光晶体热效应　；参考：《山东师范大学》2015年硕士论文

【摘要】：自上世纪六十年代激光技术产生以来，激光技术已经在各个领域内影响着人们的生活和生产方式。高功率半导体泵浦固体激光器成为现阶段发展最快的激光器，它因结构紧凑、工作稳定、使用寿命长、光束质量好、效率高等优点成为新型激光器研发的焦点。半导体泵浦固体激光器广泛应用于材料加工、医学治疗、军事武器、空间通讯、空间测量以及光信息处理等方面。因为该型激光器使用二极管激光器替代了传统的闪光灯作为泵浦源，使激光泵浦技术取得巨大突破，这就为进一步提高固体激光器的输出功率和效率提供了有利的技术保障。现在半导体泵浦固体激光器的研究主要集中在如何提高激光器的输出功率和获得高质量激光束等方面，而提高这些品质的主要障碍来自于激光晶体的热效应。所以，对于激光晶体热效应的研究，，以及根据晶体热效对谐振腔性能的影响来设计谐振腔已经成为全固态激光器研究的一个重要方面。本文对激光晶体的热效应进行了理论分析，构建了激光晶体热效应的模型，建立了边界条件，并对Nd:YVO4晶体内部的温度场进行了模拟，对热效应对光程差的影响也进行了理论分析，同时分析了激光晶体在泵浦光照射下热焦距的变化。根据热焦距的变化规律，对激光谐振腔Z型腔进行了设计。本文对调Q锁模技术进行了简单的介绍，本文首次研究了以多壁碳纳米管（MWCNT）为饱和吸收体，Nd:YAG被动调Q锁模激光器的输出特性。其主要内容可概括如下： 1．第一章简单介绍了激光器的发展历史、依据不同分类标准对激光器进行简单分类以及简单介绍了全固态固体激光器特点，着重介绍了全固态激光器与传统激光器相比的所表现出来的优点；介绍了调Q技术原理以及调Q的分类和优缺点；介绍了锁模技术以及锁模技术的分类；介绍了谐振腔的作用原理以及不同的谐振腔所具有的特点；还介绍了激光晶体热效应的产生原理以及对激光器的影响。 2．第二章对激光晶体的材料进行了简单介绍，主要介绍了Nd:YAG和Nd:YVO4的结构特性以及各项性能参数；介绍了碳纳米管饱和吸收体的特性以及作为调Q元器件的所具有的特点。 3．第三章详细介绍并分析了热效应产生的原因，包括对热应力效应、热透镜效应以及双折射效应的介绍分析，同时介绍了如何降低热效应对激光器的影响。建立晶体热效应的模型，提出边界条件并列出泊松方程组，对热效应进行计算机模拟。 4．第四章根据激光晶体热效应带来的热焦距变化，列出传导矩阵，根据矩阵设计Z形谐振腔，并分析谐振腔的性能参数。 5．第五章实验研究了Nd:YAG\MWCNT被动调Q锁模特性。首先研究了Nd:YAG激光器连续运转下与插入饱和吸收体调Q锁模之后功斜效率的变化；其次研究了激光脉冲重复频率和调Q包络脉冲宽度随泵浦功率变化；最后研究了锁模脉冲宽度随泵浦功率的变化。
[Abstract]:Since the laser technology has been developed in the 1960s , the laser technology has influenced people ' s life and production mode in various fields . The high power semiconductor pump solid laser has become the focus of the new laser research and development . The semiconductor pump solid laser has been widely used in material processing , medical treatment , military weapons , space communication , space measurement and optical information processing .

In this paper , the thermal effect of the laser crystal is theoretically analyzed , the thermal effect of the laser crystal is modeled , the boundary conditions are established , and the temperature field in the Nd : YVO 4 crystal is simulated .

1 . The first chapter introduces briefly the history of laser development , the simple classification of the laser according to different classification standards and the simple introduction of the characteristics of the solid - state solid - state laser , and emphasizes the advantages of the solid - state laser compared with the conventional laser ;
This paper introduces the principle of Q - Q technology and the classification and advantages and disadvantages of Q - Q .
This paper introduces the technology of lock mould and the classification of mould locking technology .
The principle of resonant cavity and its characteristics are introduced .
The principle of laser crystal thermal effect and its effect on laser are also introduced .

2 . The second chapter briefly introduces the material of Nd : YAG and Nd : YVO 4 and the performance parameters of Nd : YAG and Nd : YVO 4 .
The characteristics of carbon nanotube saturated absorber and its characteristics are introduced .

3 . The third chapter introduces and analyzes the causes of thermal effect , including the introduction and analysis of thermal stress effect , thermal lens effect and birefringence effect , and introduces how to reduce the influence of thermal effect on the laser .

4 . In chapter 4 , according to the change of thermal focal length brought by the thermal effect of the laser crystal , the conduction matrix is listed , Z - shaped resonator is designed according to the matrix , and the performance parameters of the resonant cavity are analyzed .

5 . In chapter 5 , Nd : YAGMWCNT passively Q - locked model is studied . Firstly , the change of the work efficiency of Nd : YAG laser after Q - locking is studied under continuous operation of Nd : YAG laser .
Secondly , the repetition frequency of laser pulse and the pulse width of Q - Q envelope are studied .
Finally , the variation of the pulse width of the lock mode with the pump power is studied .

【学位授予单位】：山东师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN248

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