掺钕钒酸钇单晶光谱与激光特性* 孟宪林 张怀金 祝 俐 吕孟凯提要:测量了掺钕钒酸钇(Nd∶YVO4)单晶的吸收光谱、发射光谱和荧光寿命,进行了激光二极管(LD)泵浦激光实验。Nd∶YVO4激光器理想的泵浦光是波长808.6nm的π偏振光;Nd∶YVO4晶体主发射峰波长为1064.3nm;含Nd原子浓度为1.22%的Nd∶YVO4晶体荧光寿命为95μs;泵浦阈值功率为20mW,斜效率为56.39%。研究结论:Nd∶YVO4晶体是制作LD泵浦全固态激光器的理想材料。 Spectra and Laser Properties of Nd∶YVO4 Single Crystal Meng Xianlin Zhang Huaijin Zhu Li Lu Mengkai Abstract The absorption spectra,emission spectra and fluorescence lifetimes of Nd∶YVO4 single crystals were measured.The laser experiments of Nd∶YVO4 crystal samples pumped by laser diode (LD) were demonstrated.π polarization light with wavelength of 808.6nm is the best pumping light for Nd∶YVO4 lasers.The wavelength at main emission peak of Nd∶YVO4 crystal is 1064.3nm.The fluorescence lifetime of 1.22 at% Nd doped YVO4 crystal is 95μs.The pumping threshold power is about 20 mW and the slope efficiency is 56.39%.From the investigation we can draw a conclusion:Nd∶YVO4 crystal is an ideal material for all solid state lasers pumped by LD. |
Fig.1 The polarization absorption spectra |
Fig.2 The emission spectra of Nd∶YVO4 single crystal 2.4 荧光寿命 Table 1 The fluorescence lifetimes of Nd∶YVO4 single crystals |
Sample | Nd concentration in melt (at%) | Nd concentration in crystal(at%) | Fluorescence lifetime(μs) |
No.1 | 1.0 | 0.64 | 105 |
No.2 | 2.0 | 1.22 | 95 |
No.3 | 3.0 | 1.89 | 85 |
Table 2 The pumping thresholds of Nd∶YVO4 single crystals |
Sample | No.1 | No.2 | No.3 | No.4 | No.5 | No.6 | No.7 |
Threshold (mW) | 21 | 20 | 26 | 19 | 21 | 20 | 21 |
Table 3 The main power data of Nd∶YVO4 lasers |
Pump power (mW) | Output power (mW) | ||||||
No.1 | No.2 | No.3 | No.4 | No.5 | No.6 | No.7 | |
274 | 95 | 92 | 94 | 88 | 95 | 105 | 89 |
630 | 234 | 233 | 249 | 239 | 240 | 249 | 234 |
980 | 393 | 401 | 433 | 417 | 419 | 430 | 405 |
1320 | 557 | 573 | 611 | 585 | 616 | 631 | 603 |
1660 | 710 | 731 | 759 | 749 | 782 | 808 | 769 |
1840 | 784 | 813 | 833 | 817 | 905 | 921 | 848 |
根据表3数据作出的未退火样品和退火样品输入、输出功率关系示于图3和图4。 |
Fig.3 Output powers of unannealed Nd∶YVO4 |
Fig.4 Output powers of annealed Nd∶YVO4 对表3全部数据进行拟合,求得各样品激光器件的斜率示于表4。 Table 4 The slope efficiencies of Nd∶YVO4 lasers |
Sample | No.1 | No.2 | No.3 | No.4 | No.5 | No.6 | No.7 |
Slope efficiency (%) | 44.74 | 46.79 | 48.08 | 47.52 | 51.97 | 52.76 | 49.72 |
Table 5 The slope efficiencies of Nd∶YVO4 lasers when pump powers are higher than 1W |
Sample | No.1 | No.2 | No.3 | No.4 | No.5 | No.6 | No.7 |
Slope efficiency (%) | 45.56 | 47.84 | 46.39 | 46.98 | 55.34 | 56.39 | 51.59 |
ηs=(T/Lc)(νL/νp)ηp 其中T为输出镜的透过率,Lc为腔内全部的被动损耗,νL和νp分别是振荡光和泵浦光的频率,ηp是泵浦效率。考虑到我们实验条件下,T,Lc,νL和νp均为常数,导致ηs提高的原因显然是ηp的提高。这就是说,晶体退火可以提高其器件的泵浦效率。由于各样品实验用的是同一个LD,系统内其他条件完全一样,因此ηp的提高只能是工作物质内部得到改善的结果。 * 山东省自然科学基金资助项目。 作者单位:孟宪林 张怀金 祝 俐 吕孟凯 1 O'Conner J R.Unusual Crystal-field Energy Level and Efficient Laser Properties of YVO4∶Nd.Appl.Phys.Lett.,1966,9(11):407 本文1998年9月10日收到,1998年10月25日收到修改稿。 |
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