【作者】 徐翠莲；

【导师】 曲士良； 潘玉寨；

【作者基本信息】 哈尔滨工业大学 ， 光学， 2008， 硕士

【摘要】 激光二极管（LD）泵浦的固体激光器具有效率高、光束质量好、结构紧凑、寿命长等优点,在军事、医学、信息、科研等领域具有广泛的用途。其中,以掺铒玻璃为介质的激光器能发射1.54μm附近的激光,共掺Yb³⁺可以大大提高激光效率。这种激光器被广泛地应用于光通讯、光传感、人眼安全激光测距等方面。本文对LD端泵浦Er³⁺/Yb³⁺共掺磷酸盐玻璃固体激光器进行了理论分析和实验研究,获得最大30mW 1.54μm激光的输出,光-光转换效率1.6%。具体研究内容如下:1.根据速率方程理论建立1.54μm激光运转的速率方程模型,并推导出稳态工作时泵浦的阈值功率、输出功率、斜率效率。对Er³⁺/Yb³⁺激光三能级系统速率方程进行分析,得出腔长、输出镜的透过率、泵浦光斑半径、腔内往返损耗对输入输出功率关系及阈值的影响。得出激光运转的优化条件。2.指明了设计耦合透镜组的方式,得到了光腰位置、光腰半径随物距s1的变化关系;光腰位置、晶体内部平均泵浦光斑半径与耦合透镜焦距的变化关系。3.采用ABCD传输矩阵对有源平平腔,平凹腔进行数值计算,分析了谐振腔内激光光斑及腔体的稳定性。得出谐振腔内振荡光斑半径、稳定参数与输入功率、热透镜焦距的关系,稳定性参数与腔长的变化关系;确定谐振腔长度在20mm⁶0mm内最稳定,泵浦功率小于10W时,平凹腔的稳定性优与平平腔,平凹腔内光斑半径ω的取值较小且变化较缓慢。4.在理论分析的基础上,以光纤耦合输出半导体激光器作为泵浦源,Er³⁺/Yb³⁺共掺磷酸盐玻璃为工作介质,成功地实现平平腔、平凹腔在常温下连续输出1.54μm激光。考虑到弯月型输出镜对于光束质量的改善作用,本文亦采用弯月型输出镜进行了实验,输入功率为3.05W时得到30mW的1.54μm激光的连续输出。更多还原

【Abstract】 Laser-diode-pumped solid-state laser（DPSSL）, owing to their advantages such as high efficiency, high beam quality and long lifetime, etc., has been widely used in the fields of military affairs, medicine, information and so on. The solid-state Er³⁺:Yb³⁺ codoped glass laser generating eye-safe wavelengths around 1.54μm is considerably promising for various applications including imaging, optical communications, ladar, spectroscopy and remote sensing. The Yb³⁺-ion concentration helps in the pump absorption. The experimental and theoretical studies on laser-diode end-pumped CW Er³⁺:Yb³⁺ codoped phosphate glass laser are presented in this paper. The maximum output power of 30mW and the conversion efficiency up to 1.6% are obtained。The main researches are as follows :1. The spectra properties and energy level structure of Er³⁺:Yb³⁺ codoped phosphate glass are presented. We construe the theory of three-level system rate equations and demonstrate some parameters for optimizing the laser operation. In order to guide the actual work, we analyze the influence of cavity length on the threshold, slope efficiency and output power, also the influence of output mirror transmission, round-trip dissipative optical loss, waist of pump beam are researched by numerical calculus.2. We use the ABCD matrix theory to analyze the coupling system, and point out how to adjust the parameters of the lens to make the radius of pumping beam optimized. The relation of average pump laser radius in glass and two lens focus is obtained, as well as the relation of image distance s2 and object distance s1.3. The cavity is designed by the ABCD matrix theory. Considering the thermal-lensing effect, the stability of laser cavity and 1.54μm laser beam waist are analyzed to guide optimized cavity parameters. It is shown that the stability of flat-concave cavity is better than the flat-flat cavity’s with the lower pump power.4. According to the above analysis, we designed a LD end-pumped all-solid-state Er³⁺:Yb³⁺ codoped phosphate glass laser, with maximal output power of 30mW/1.54μm. It is shown that the flat-concave cavity is less sensitive to thermal-lensing effect and maladjustment of mirrors than the flat-flat cavity. The output power, the slope efficiency and the threshold power of the laser with the flat-concave cavity changed tittle when the length of cavity changed. So flat-concave cavity is better than the flat-flat cavity, which is consistent with the theory analysis.更多还原