LD泵浦3微米Er固体激光器输出特性研究
发布时间：2018-10-14 21:00
【摘要】：2.5-3μm中红外波段的激光在激光医疗技术、遥感技术、大气环境监测以及光电对抗等方面的应用前景十分诱人,尤其是涉及被水强吸收和要求对生物组织穿透深度只有几微米的方面。在高浓度掺Er情况下,Er激光介质发射波长在3μm附近的波段内,恰好处于水的吸收峰附近。本文分析了Er激光介质3μm附近波段的光谱,包括掺杂浓度为50at.%的Er:YAG晶体和掺杂浓度为10at.%的Er:YAG陶瓷。另外对掺杂浓度为30at.%的Er:YSGG晶体的光谱也做了简单说明。在此基础上,对LD端面泵浦的高掺Er:YAG晶体和陶瓷的输出特性展开了研究。首先介绍了Er:YAG晶体的物理特性,之后简单分析了Er3+的能级结构。在此基础上,对Er:YAG晶体的吸收光谱和荧光光谱进行了计算,得出吸收截面和发射截面,进一步计算还得到了增益截面和增益系数并对此进行了分析。另外,利用J-O理论计算了Er:YAG晶体的光谱参数,包括电偶极跃迁的振子强度,自发发射跃迁几率,荧光寿命,跃迁荧光分支比以及积分发射截面等。对Er:YAG陶瓷的光谱进行分析的方法与Er:YAG晶体类似。然后,以热传导方程为基础,建立了单端泵浦的柱状热分析模型,从理论上计算和模拟了Er:YAG晶体和Er:YAG陶瓷激光介质内的温度分布,然后分析了它们的热应力和最大泵浦功率。最后,分析了Er3+的能级跃迁并讨论了掺杂浓度对输出波长的影响。在此基础上,建立了包括速率方程在内的Er:YAG固体激光器理论模型,进一步讨论了掺杂浓度的影响,并数值模拟了各种参数对Er:YAG固体激光器输出的影响。在完成这些理论分析后,设计了谐振腔并进行了初步实验。通过对单掺Er激光介质3μm波段光谱特性及输出性能的研究,发现输出较高功率、波长为2.94μm的激光所需要的条件是:较短的腔长、尽量低的腔内损耗、高反射率的输出镜,另外还要设法减小激光介质的热效应或增大激光介质所能承受的最大应力。同时,这些研究也为3μm波段相关激光器的研究提供了一定参考。
[Abstract]:2.5-3 渭 m mid-infrared laser has a very attractive prospect in laser medical technology, remote sensing technology, atmospheric environment monitoring and optoelectronic countermeasure, etc. In particular, it involves water absorption and requires a penetration depth of only a few microns to biological tissue. In the case of high concentration of Er doped, the emission wavelength of Er laser medium is about 3 渭 m, which is just near the absorption peak of water. In this paper, the spectra of Er laser medium near 3 渭 m are analyzed, including 50 at.% doped Er:YAG crystals and 10at.% doped Er:YAG ceramics. In addition, the spectra of Er:YSGG crystals with doping concentration of 30 at.% are also explained. On this basis, the output characteristics of highly doped Er:YAG crystals and ceramics pumped by LD are investigated. Firstly, the physical properties of Er:YAG crystal are introduced, and then the energy level structure of Er3 is analyzed briefly. On this basis, the absorption and fluorescence spectra of Er:YAG crystal are calculated, the absorption cross sections and emission cross sections are obtained, and the gain cross sections and gain coefficients are also calculated and analyzed. In addition, the spectral parameters of Er:YAG crystal are calculated by J-O theory, including the oscillator intensity of dipole transition, spontaneous emission transition probability, fluorescence lifetime, transition fluorescence branch ratio and integral emission cross section. The method of spectrum analysis of Er:YAG ceramics is similar to that of Er:YAG crystals. Then, based on the heat conduction equation, a single end pumped cylindrical thermal analysis model is established. The temperature distribution in Er:YAG crystal and Er:YAG ceramic laser medium is calculated and simulated theoretically, and their thermal stress and maximum pump power are analyzed. Finally, the energy level transition of Er3 is analyzed and the influence of doping concentration on the output wavelength is discussed. On this basis, the theoretical model of Er:YAG solid-state laser, including rate equation, is established. The influence of doping concentration on the output of Er:YAG solid-state laser is further discussed. The effects of various parameters on the output of Er:YAG solid-state laser are numerically simulated. After the theoretical analysis, the resonator is designed and a preliminary experiment is carried out. By studying the spectral characteristics and output performance of single doped Er laser dielectric at 3 渭 m band, it is found that the laser with high output power and wavelength of 2.94 渭 m requires the following conditions: shorter cavity length, lower intracavity loss, and higher reflectivity output mirror. In addition, it is necessary to reduce the thermal effect of the laser medium or to increase the maximum stress that the laser medium can withstand. At the same time, these studies also provide a certain reference for the study of 3 渭 m wavelength correlation lasers.
【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
本文编号：2271630
[Abstract]:2.5-3 渭 m mid-infrared laser has a very attractive prospect in laser medical technology, remote sensing technology, atmospheric environment monitoring and optoelectronic countermeasure, etc. In particular, it involves water absorption and requires a penetration depth of only a few microns to biological tissue. In the case of high concentration of Er doped, the emission wavelength of Er laser medium is about 3 渭 m, which is just near the absorption peak of water. In this paper, the spectra of Er laser medium near 3 渭 m are analyzed, including 50 at.% doped Er:YAG crystals and 10at.% doped Er:YAG ceramics. In addition, the spectra of Er:YSGG crystals with doping concentration of 30 at.% are also explained. On this basis, the output characteristics of highly doped Er:YAG crystals and ceramics pumped by LD are investigated. Firstly, the physical properties of Er:YAG crystal are introduced, and then the energy level structure of Er3 is analyzed briefly. On this basis, the absorption and fluorescence spectra of Er:YAG crystal are calculated, the absorption cross sections and emission cross sections are obtained, and the gain cross sections and gain coefficients are also calculated and analyzed. In addition, the spectral parameters of Er:YAG crystal are calculated by J-O theory, including the oscillator intensity of dipole transition, spontaneous emission transition probability, fluorescence lifetime, transition fluorescence branch ratio and integral emission cross section. The method of spectrum analysis of Er:YAG ceramics is similar to that of Er:YAG crystals. Then, based on the heat conduction equation, a single end pumped cylindrical thermal analysis model is established. The temperature distribution in Er:YAG crystal and Er:YAG ceramic laser medium is calculated and simulated theoretically, and their thermal stress and maximum pump power are analyzed. Finally, the energy level transition of Er3 is analyzed and the influence of doping concentration on the output wavelength is discussed. On this basis, the theoretical model of Er:YAG solid-state laser, including rate equation, is established. The influence of doping concentration on the output of Er:YAG solid-state laser is further discussed. The effects of various parameters on the output of Er:YAG solid-state laser are numerically simulated. After the theoretical analysis, the resonator is designed and a preliminary experiment is carried out. By studying the spectral characteristics and output performance of single doped Er laser dielectric at 3 渭 m band, it is found that the laser with high output power and wavelength of 2.94 渭 m requires the following conditions: shorter cavity length, lower intracavity loss, and higher reflectivity output mirror. In addition, it is necessary to reduce the thermal effect of the laser medium or to increase the maximum stress that the laser medium can withstand. At the same time, these studies also provide a certain reference for the study of 3 渭 m wavelength correlation lasers.
【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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