掺钕钆镓石榴石(Nd3+∶Gd3Ga5O12, 简称Nd∶GGG)激光晶体是固体热容激光器的首选工作物质。 采用提拉法生长了Nd∶GGG晶体, 测试了晶体的吸收及荧光光谱, 并利用J-O理论计算了晶体的吸收及发射截面、 强度参数、 辐射跃迁概率、 荧光分支比、 荧光寿命等光谱参数。 吸收光谱测试及计算结果发现, Nd∶GGG晶体的最强吸收峰位于808 nm附近, 主峰808 nm的吸收截面积σabs=4.35×10-20 cm2, 吸收线宽FWHM为8 nm, 并且吸收峰强度随掺杂离子浓度的增加而增加。 荧光光谱测试及计算结果表明, 晶体的最强荧光发射峰位于1 062 nm附近, 是Nd3+的4F3/2-4I11/2能级跃迁产生的荧光发射。 主发射峰1 062 nm辐射跃迁概率AJJ′=1 832.01 s-1, 荧光分支比βJJ＝45.07％, 荧光寿命τ＝250 μs, 受激发射截面σ(λ)=21.58×10-20 cm2, 较大的荧光分支比和受激发射截面易实现4F3/2-4I11/2通道的激光运转。

Neodymium-doped gadolinium gallium garnet (Nd∶GGG)crystal is the best operation material of solid-state heat-capacity laser. In the present paper, Nd∶GGG single crystal was grown by Czochralski (Cz)method. Fluorescence spectra and absorption spectra were measured. At the same time, the spectral parameters of Nd∶GGG laser crystal were calculated by Judd-Ofelt theory, including absorption and emission cross-section, intensity parameters, radiative transition probability, fluorescence branch ratio and fluorescent lifetime. According to the measurement and calculation of absorption spectra, it is illustrated that the main absorption peak of Nd∶GGG crystal was at near 808 nm, the absorption cross section of the main peak at 808 nm σabs was equal to 4.35×10-20 cm2. The FWHM of absorption line-width was equal to 8 nm, and the absorption intensity became stronger with the increase in Nd3+ ions concentration. According to the measurement and calculation of fluorescence spectra, the fluorescence emission peak was at near 1 062 nm, which corresponds to 4F3/2-4I11/2 emission band of Nd3+ ions. The radiative transition probabilityof the main emission peak at 1 062 nm AJJ′ was equal to 1 832.01 s-1. The fluorescence branch ratio βJJ was equal to 45.07％. The fluorescence lifetime τ was equal to 250 μs. The stimulated emission cross section σ(λ) was equal to 21.58×10-20 cm2. The laser operation of 4F3/2-4I11/2 transition can be realized due to the larger fluorescence branch ratio and stimulated emission cross section.