新型激光晶体Nd:GSAG和Cr,Nd:GSAG的生长及光学性能研究

发布时间：2018-10-16 22:10

【摘要】：高均匀性大尺寸激光晶体是全固态高功率激光发展的重要基础,而空间激光则需要发展具有抗辐射性能的高效激光晶体。Nd3+在GSAG的分凝系数约为YAG中的三倍,且熔点比YAG略低,有望制备出大尺寸高均匀性激光晶体元件,同时其与具有优良抗辐照性能的Cr,Nd:GSGG结构和性能类似,因而,论文选取Nd和Nd,Cr掺杂的GSAG作为研究对象,拟探索大尺寸高均匀性激光晶体和具有优良抗辐射性能的激光晶体。主要研究内容和结果如下:一、采用提拉法成功生长出了直径为Φ30mm的Nd:GSAG晶体,测定了Nd3+在GSAG中的有效分凝系数,通过Rietveld全谱拟合得到了结构参数,研究了 Nd:GSAG室温下的吸收和发光。Nd3+在GSAG的有效分凝系数为0.53,最强吸收峰位于808.6nm处,吸收截面为3.44×10-20cm2,跃迁强度参数Ωt(t=2,4,6)为 0.263×10-20cm2、3.010×10-20cm2、3.648×10-20cm2;它的最强发射峰位于 1060nm处,1060nm、941.5nm 的发射截面分别为 6.32×10-20cm2、2.77×10-20cm2。相应激光上能级4F3/2的寿命为258μs。用808nm连续半导体激光器(LD)作为泵浦源研究了 2mm×2mm×6mm的Nd:GSAG的1.06μm激光性能,其阈值为2.139W,斜效率为8.9%,最高输出功率为0.462W,光-光转换效率为5.12%。此外,还测定了 Nd:GSAG晶体在297K-748K范围内的热扩散系数,计算得到其热导率从 4.51 W/(m · K)变化到 2.80W/(m · K)。二、在Nd:GSAG中掺入0.1at%的Cr3+,采用提拉法成功生长出了直径为Φ30mm的光学质量良好的Cr,Nd:GSAG晶体。最强吸收峰位于808.6nm处,吸收截面为3.38×10-20cm2。不计Cr,Nd:GSAG的吸收光谱中Nd3+和Cr3+重叠的吸收带,拟合得到Cr,Nd:GSAG中Nd3+的强度参量Ωt(t=2,4,6)为0.380×10-20cm2、2.286×10-20cm2、3.306×10-20cm2;Cr,Nd:GSAG 最强发射峰位于 1060nm 处,在1060nm、941.5nm 的发射截面分别为 5.98×10-20cm2、2.60×10-20cm2,室温下Cr,Nd:GSAG的4F3/2能级寿命为274μs。用808nm连续半导体激光器(LD)作为泵浦源研究了 2mm×2mm×6mm的Cr,Nd:GSAG的1.06μm激光性能,其阈值为1.233W,斜效率为6.73%,最高输出功率为0.513W,光-光转换效率为5.78%。三、利用60Co伽马射线源对Nd:GSAG和Cr,Nd:GSAG进行了 2Mrad、1OMrad、20Mrad辐照剂量的辐照,对比测试了辐照与未辐照样品的吸收、发光,表明这两种晶体可能具有抗辐照性能,而掺杂Cr3+有利于增强Nd:GSAG的抗辐照性能。
[Abstract]:High uniformity and large size laser crystals are the important basis for the development of all-solid-state high-power lasers, while space lasers need to develop high-efficiency laser crystals with anti-radiation properties. The coagulation coefficient of Nd3 in GSAG is about three times that of YAG, and the melting point is slightly lower than that of YAG. It is expected that the large size and high uniformity laser crystal element will be prepared, and it is similar to the structure and performance of Cr,Nd:GSGG with excellent radiation resistance. Therefore, Nd and Nd,Cr doped GSAG are selected as the research objects in this paper. Large size and high uniformity laser crystals and laser crystals with excellent radiation resistance are to be explored. The main contents and results are as follows: firstly, Nd:GSAG crystals with diameter 桅 30mm have been successfully grown by Czochralski method, the effective coagulation coefficients of Nd3 in GSAG have been measured, and the structural parameters have been obtained by Rietveld full-spectrum fitting. The absorption and luminescence of Nd:GSAG at room temperature are studied. The effective segregation coefficient of Nd3 at room temperature is 0.53, the strongest absorption peak is at 808.6nm, the absorption cross section is 3.44 脳 10-20cm2, the transition intensity parameter 惟 t (ttm2m2c2c2c2c2c2n) is 3.010 脳 10-20cm2n 2, the strongest emission peak is at 1060nm, the emission cross section of 1060nmmnm941.5nm is 6.32 脳 10-20cm2.77 脳 10-20cm2cm2.77 脳 10-20cm2.77 脳 10-20cm2.77 脳 10-20cm2.77 脳 10-20cm2.77 脳 10-20cm2.77 脳 10-20cm2.77 脳 10-20cm2.77 脳 10-20cm2.77 脳 10-20cm2.77 脳 10-20cm2, respectively. The lifetime of the corresponding laser upper level 4F3/2 is 258 渭 s. The 808nm CW semiconductor laser (LD) is used as the pump source to study the 1.06 渭 m laser performance of 2mm 脳 2mm 脳 6mm Nd:GSAG. The threshold value is 2.139 W, the slope efficiency is 8.9 W, the maximum output power is 0.462 W, and the optical-optical conversion efficiency is 5.12 W. In addition, the thermal diffusivity of Nd:GSAG crystal in the range of 297K-748K was measured. The thermal conductivity of Nd:GSAG crystal changed from 4.51 W / (m K) to 2.80W/ (m K). Secondly, Cr,Nd:GSAG crystals with diameter 桅 30mm were successfully grown by Czochralski method with 0.1 at% Cr3 in Nd:GSAG. The strongest absorption peak is located at 808.6nm, and the absorption cross section is 3.38 脳 10 ~ (-20) cm ~ (2). Regardless of the overlapping absorption bands of Nd3 and Cr3 in the Cr,Nd:GSAG absorption spectra, the intensity parameter 惟 t (ttn2m2m2h2) of Nd3 in Cr,Nd:GSAG is 0.380 脳 10-20cm2n ~ (2) 2.286 脳 10 ~ (-20) cm ~ (2) C ~ (2 +) 3.306 脳 10 ~ (-20) cm _ (2) C _ (2) C ~ (2 +) emission peak is located at 1060nm, and the emission cross section at 1060 nm is 5.98 脳 10 ~ (-20) cm ~ (-2) ~ (2) (2.60 脳 10 ~ (-20) cm ~ (-2) respectively. The 4F3/2 lifetime of Cr,Nd:GSAG at room temperature is 274 渭 s ~ (-1). The 808nm CW semiconductor laser (LD) is used as the pump source to study the 1.06 渭 m laser performance of the Cr,Nd:GSAG of 2mm 脳 2mm 脳 6mm. The threshold value is 1.233 W, the slope efficiency is 6.73 W, the maximum output power is 0.513 W, and the optical-optical conversion efficiency is 5.78 W. (3) Nd:GSAG and Cr,Nd:GSAG were irradiated by 60Co gamma ray source. The absorption of irradiated and unirradiated samples was compared with that of unirradiated samples. The results showed that the two crystals may have the ability to resist irradiation. Doping Cr3 is beneficial to enhance the radiation resistance of Nd:GSAG.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O734

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