LD端面泵浦窄线宽Tm:YLF激光器研究

发布时间：2018-11-13 10:00

【摘要】：2μm波段人眼安全激光处于大气窗口,广泛应用于激光医疗、环境监测和光通信等领域。此外,2μm激光器可作为3~5μm和8~12μm中红外光参量振荡器和光参量放大器的抽运源。掺Ho3+晶体是产生高性能2μm激光的首选工作物质,而1.9μm Tm:YLF激光器是其理想泵浦源。因此,获得高功率、高效率且高稳定性的1.9μm激光输出至关重要。本论文以理论模拟为基础,以体光栅为谐振腔镜,结合腔内双F-P标准具,在保证高功率和高稳定性的基础上获得窄线宽激光输出。理论方面,介绍了Tm:YLF晶体的物理、光谱特性,基于Tm:YLF激光器准三能级速率方程模型,通过简化方程组最终得到激光器阈值、输出功率及斜率效率的表达式,模拟并分析了上转换效应、交叉弛豫、以及晶体掺杂浓度和长度对Tm:YLF激光器输出特性的影响,为后续激光器的设计与实验奠定理论基础。设计方面,基于Tm:YLF晶体热模型,对晶体温度场分布进行解析推导并模拟各参数晶体热分布,综合分析后选取晶体尺寸为3×3×12mm3,掺杂浓度为3.5at.%;对“L型”谐振腔不同参数条件下模式匹配、稳定性进行模拟,设计出谐振腔的参数范围,为后续实验研究奠定基础;对窄线宽元件体光栅和F-P标准具进行参数设计,选取体光栅端面尺寸为6×6mm2,厚度为5.5±1.5nm,双F-P标准具厚度分别为0.1mm和1mm。实验方面,搭建LD端面泵浦Tm:YLF激光器,并依次研究以体光栅为腔镜时不同谐振腔长、输出镜透过率和曲率半径对激光输出特性的影响,确定最佳谐振腔参数,并在腔内插入双F-P标准具,实现了17.8W的1908.55nm稳定性较高的激光输出,线宽仅为0.10nm,且波长最大波动范围仅0.34nm。激光器相应的斜率效率和光光转换效率分别为42.89%和35.86%。
[Abstract]:The 2 渭 m band human eye safe laser is in the atmosphere window, and is widely used in laser medical treatment, environmental monitoring and optical communication. In addition, the 2 渭 m laser can be used as the pump source of the infrared parametric oscillator and optical parametric amplifier of 3 5 渭 m and 8 渭 m 12 渭 m. Ho3 doped crystal is the preferred working material to produce high performance 2 渭 m laser, and 1.9 渭 m Tm:YLF laser is the ideal pump source. Therefore, it is very important to obtain 1.9 渭 m laser output with high power, high efficiency and high stability. In this paper, based on theoretical simulation, the narrow linewidth laser output is obtained on the basis of high power and high stability by using volume grating as resonant mirror and double F-P standard in cavity. In theory, the physical and spectral characteristics of Tm:YLF crystal are introduced. Based on the quasi three level rate equation model of Tm:YLF laser, the expressions of threshold, output power and slope efficiency are obtained by simplifying the equations. The effects of upconversion effect, cross relaxation, crystal doping concentration and length on the output characteristics of Tm:YLF laser are simulated and analyzed, which lays a theoretical foundation for the design and experiment of the subsequent laser. On the basis of the Tm:YLF crystal thermal model, the crystal temperature distribution is analyzed and simulated. The crystal size is 3 脳 3 脳 12 mm 3 and the doping concentration is 3.5 at. The mode matching and stability of the "L-type" resonator under different parameters are simulated, and the parameters range of the resonator is designed, which lays a foundation for further experimental research. The size of the volume grating and F-P standard device are 6 脳 6 mm ~ 2 and 5.5 卤1.5 nm respectively, and the thickness of the double F-P standard device is 0.1mm and 1 mm respectively, and the size of the volume grating is 6 脳 6 mm ~ 2 and the thickness is 5.5 卤1.5 nm. In experiment, LD end-pumped Tm:YLF laser is built, and the effects of different cavity length, output mirror transmittance and curvature radius on the laser output characteristics are studied in turn, and the optimal cavity parameters are determined. A dual F-P standard device is inserted into the cavity to achieve a 17.8 W 1908.55nm laser output with a high stability. The linewidth is only 0.10 nm, and the maximum wavelength fluctuation range is only 0.34 nm. The slope efficiency and optical conversion efficiency of the laser are 42.89% and 35.86% respectively.
【学位授予单位】：长春理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN248

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