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chi20191128上海光机所于春雷557641Compared with other lasers, fiber lasers have become one of the most popular laser technologies due to two advantages: high average power and high beam quality. Yb3+ and Er3+ doped silica optical fibers are the two most common optical fiber materials and are widely used in the fields of industry, communication, medical, scientific research, and national defense. Double-clad Yb3+ doped silica fiber lasers have been leading the way in the development of high power due to using cladding pumps, a large absorption of pump light and a small quantum loss. However, on the one hand, due to the high power, the thermal effects (including thermal lenses, nonlinearity, heat loss, etc.) also limit the further development of high-power fiber lasers. On the other hand, for high power erbium doped fiber lasers, due to the large quantum loss of Er3+ emission and concentration quenching, the laser output power has been in the order of hundreds of watts, which severely limits the performance of Er3+ doped fiber in high-power application fields. In recent years, our laboratory has prepared high uniformity, high concentration Er3+ doped silica glass and optical fibers with the help of Sol-gel and high-temperature powder sintering technology, which has great application prospects in high-power fiber lasers. Based on previous research, the main purpose of this paper is to study the effect of temperature on the spectral and laser properties of Yb3+ and Er3+ doped silica glass and optical fibers. The study will provides some reference to study the performance for Yb3+ and Er3+ doped fiber lasers under high-power laser operation. This thesis consists of six parts: The first chapter is mainly a literature review section, which introduces the application of high-power fiber lasers and their thermal effects, the structure of silica glass, the energy level structure and spectral properties of Yb3+ and Er3+, and the significance of research on large-mode-field silica fibers. Putting forward the research ideas and content of this paper based on the thermal effect of high power fiber laser. The second chapter mainly introduces the measurement of physicochemical properties, structural composition test and spectroscopic calculation of rare earth doped glass. The third chapter studies the effect of temperature on the spectral and laser properties of Yb3+ doped silica glass and fiber. First, as the temperature increases from 20°C to 140°C, the absorption cross section of Yb3+ decreases at ~915nm and 975nm, the emission cross section and fluorescence intensity of Yb3+ decrease at 976nm and ~1034 nm, and the fluorescence of Yb3+ decreases. The lifetime decreases at ~ 1080 nm. Secondly, for a 12cm Yb3+ doped fiber laser and pumped with a ~975nm LD , when the temperature increases from 20 ℃ to 90 ℃, the laser efficiency with operating at 1035.7 nm reduces from 60.8% to 59.1%, while the laser efficiency with operating with 1061nm reduces from 63.3% to 48.7% . Furthermore, when the pump power is below 80mW and the fiber temperature is up to 160°C, the laser operating at 1061nm has almost no laser signal output, while the laser operating at 1035.7nm still has a stable laser output of 17 mW at 370 °C. Therefore, the Yb3+ doped fiber laser operating at 1061 nm is more sensitive to temperature than the Yb3+ doped fiber laser operating at 1035.7 nm. The fourth chapter studies the effect of temperature on the spectral and laser characteristics of Er3+ doped silica glass and fiber. At the same time, the effect of temperature on the thermal bleaching characteristics of irradiated Er3+ doped silica fiber is also studied. First, the temperature increases from 20 °C to 140 °C, the absorption cross sections at ~1480 nm and 1528 nm decreases. In addition, the full width at half maximum of fluorescence spectral at ~1.5 μm increases, the fluorescence peak is red shift and the fluorescence lifetime decreases. As the temperature increases from 20 °C to 140 °C, the emission cross section at 1528 nm decreases, and the emission cross section at 1558 nm increases, which increases the amplified spontaneous emission (ASE) effect. Third, the absorption coefficient and lifetime reduces due to the temperature rises from 20 °C to 440 °C. The output efficiency of Er3+ doped fiber laser at 1558 nm decreases from 10.8% to 6.4%; Threshold of pumping power increases from 48 mW to 77 mW. Fourth, the loss at ~1.5 μm band increases and the laser efficiency decreases at 1558 nm due to the radiation damage of Er3+ doped silica fiber. At the same time, the output power at 1558 nm of the laser can increases by thermal bleaching of the irradiated Er3+ doped silica fiber. The higher the temperature, the higher the rate of thermal bleaching. The fifth chapter studies the influence of temperature on Yb3+/Er3+ co-doped silica fiber laser. The results show that the temperature increases from 20 °C to 140 °C, unlike Yb3+ and Er3+ single-doped fiber lasers, the output power and efficiency of Yb3+/Er3+ co-doped silica fiber lasers increase at 1558 nm, and the threshold of pumping power decreases. It indicates that the speed of energy transfer process Yb3+:2F5/2→Er3+:4I11/2 increase with temperature rising. The sixth chapter summarizes the research results of this article. Pointing out the innovation points and the existing shortcomings, and putting forward the research direction of the next stage.2020atalunwen221316522465Silica glass; Thermal effects; Ytterbium doped fiber laser; Erbium doped fiber laser; Spectroscopic propertiesStudy on Effect of Temperature Dependence of Spectral and Laser Performance of Yb3+ and Er3+ Doped Silica Glass and Fibers温度对Yb3+和Er3+掺杂石英玻璃及光纤光谱和激光性能的影响研究相比于其他激光器,光纤激光以高平均功率、高光束质量两大优势成为了最热门的激光技术之一。Yb3+和 Er3+掺杂石英光纤是最常见的两种光纤材料,在工业、通信、医疗、科研、国防领域都有广泛应用。双包层Yb3+掺杂石英光纤激光器由于采用包层泵浦,且Yb3+对泵浦光的吸收大,量子亏损小等原因其在高功率发展道路上一直处于领先地位,然而,由于高功率所带来的热效应(包括热透镜,非线性,热损失等)也限制了高功率光纤激光器的进一步发展。另一方面,对于高功率掺铒光纤激光器,由于Er3+发光的量子亏损大、容易浓度猝灭等原因,激光输出功率一直处于数百瓦量级,严重限制了Er3+掺杂光纤在高功率领域的应用。近年来,实验室借助溶胶凝胶结合高温粉末烧结技术制备了高均匀性、高浓度Er3+掺杂的石英玻璃及光纤,其在高功率光纤激光方面有着很大的应用前景。在以往研究的基础上,本论文的主要目的是研究温度对Yb3+和Er3+掺杂石英玻璃及光纤光谱和激光性能的影响,从而为Yb3+和Er3+掺杂光纤激光器在高功率激光运转下的性能研究提供一定的参考。本论文包括六部分: 第一章主要是文献综述部分,介绍了高功率光纤激光器的应用及其热效应影响、石英玻璃的结构、Yb3+及Er3+的能级结构及光谱性质和大模场石英光纤的研究意义。基于高功率光纤激光器的热效应提出了本文的研究思路及内容。 第二章主要介绍稀土掺杂玻璃的物理化学性质测量、结构成分测试及光谱理论计算。 第三章研究了温度对Yb3+掺杂石英玻璃及光纤的光谱特性和激光特性影响。第一,随着温度从20℃升高至140℃,Yb3+的吸收截面在~915 nm和975 nm减小,Yb3+的发射截面和荧光强度在976 nm和~1034 nm处减小,Yb3+的荧光寿命在~1080 nm处减小。第二,对于12 cm长Yb3+掺杂光纤激光,温度从20 ℃升高至90 ℃条件下,当激光运转于1035.7 nm时,激光效率从60.8%降低至59.1%,而当激光运转于1061 nm处,激光效率从63.3%降低至48.7%。同时,当泵浦功率在80 mW以下,工作于1061 nm时,光纤温度升高至160 ℃几乎没有激光信号输出,而工作于1035.7 nm时,在370℃条件下仍然有17 mW的稳定激光输出。因此,工作于1061 nm的Yb3+掺杂光纤激光器相比工作于1035.7 nm时Yb3+掺杂光纤激光器对温度更为敏感。 第四章研究了温度对Er3+掺杂石英玻璃及光纤的光谱特性和激光特性影响,同时,初步研究了温度对辐照过的Er3+掺杂石英光纤热漂白特性的影响。结果表明:第一,温度从20℃升高至140℃,~1480 nm及1528 nm处吸收截面减小,同时,温度升高使得Er3+在~1.5 μm波段荧光半宽高增大,荧光峰红移,荧光寿命减小。第二,温度从20℃升高至140℃,1528 nm发射截面减小,1558 nm发射截面增大,放大自发辐射(ASE)效应加剧。第三,受温度升高带来的吸收系数和寿命减小,温度从20℃升高至440℃,Er3+掺杂光纤激光在1558 nm处输出效率从10.8%降至6.4%,激光泵浦阈值功率从48 mW升高至77 mW。第四,Er3+掺杂石英光纤的辐致损伤使得光纤在~1.5 μm波段损耗增大,1558 nm处激光效率降低;同时,对已辐照过的Er3+掺杂石英光纤做热漂白处理可使光纤激光在1558 nm处输出功率增大;温度越高,漂白速率越大。 第五章研究了温度对Yb3+/Er3+共掺石英光纤激光器的影响。结果表明:温度从20℃升高至140℃,不同于Yb3+和Er3+单掺光纤激光器,Yb3+/Er3+共掺石英光纤激光器的在1558 nm处输出功率以及效率增大,阈值泵浦功率减小,证实了温度升高,会导致能量传递过程Yb3+:2F5/2→Er3+:4I11/2速率增大。 第六章总结本文的研究成果,指出了创新点和存在的不足,提出了下一阶段的研究方向。石英玻璃;温度特性;掺镱光纤激光;掺铒光纤激光;光谱特性中国科学院上海光学精密机械研究所何强材料学硕士
中文题目: 温度对Yb3+和Er3+掺杂石英玻璃及光纤光谱和激光性能的影响研究
外文题目: Study on Effect of Temperature Dependence of Spectral and Laser Performance of Yb3+ and Er3+ Doped Silica Glass and Fibers
作者: 何强
导师姓名: 于春雷
学位授予机构: 中国科学院上海光学精密机械研究所
答辩时间: 20191128
中文关键词:
石英玻璃;温度特性;掺镱光纤激光;掺铒光纤激光;光谱特性
英文关键词:
Silica glass; Thermal effects; Ytterbium doped fiber laser; Erbium doped fiber laser; Spectroscopic properties
中文摘要:
英文摘要:
文献类型:学位论文
学位级别: 硕士
正文语种: chi
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