Gd3+/Y3+共掺对Nd:CaF2晶体光谱性能的影响

通过坩埚下降法生长了系列共掺Nd,Gd:CaF₂和Nd,Y:CaF₂晶体, 研究了Gd³⁺/Y³⁺共掺对Nd³⁺光谱性能以及Nd:CaF₂晶体晶胞参数的影响规律. 对于0.5 at.%Nd, x at.%Gd(x=2,5,8,10):CaF₂系列晶体, 当调控Gd³⁺掺杂浓度为2 at.%时, 具有最大的荧光寿命499 μs; 当Gd³⁺掺杂浓度为5 at.%时, 具有最大的吸收截面1.47×10^-20 cm², 最大的发射截面1.9×10^-20 cm²; 当Gd³⁺掺杂浓度为8 at.%时, 具有最佳的发射带宽29.03 nm. 对于0.6 at.%Nd, xat.%Y(x=2, 5, 8, 10):CaF₂系列晶体, Y³⁺掺杂浓度为5 at.%时, 有最大的吸收截面2.41×10^-20 cm², 最大的发射截面3.17×10^-20 cm²; 当Y³⁺掺杂浓度为10 at.%时, 具有最长的荧光寿命359.4 μs,并且具有最大发射带宽26 nm.

Effects of Gd3+/Y3+ codoping on the spectral properties of Nd:CaF2 crystals

In the last few years, Nd³⁺ doped fluoride crystals have achieved some amazing laser performances by codoping buffer ions such as Y³⁺ and Gd³⁺ ions, which lead to the changing of local structure of Nd³⁺ ions. In this work, effects of doping concentration of Gd³⁺ and Y³⁺ ions on optical properties are discussed. The relationships between spectroscopic properties and the unit cells are also discussed. Nd, Y:CaF₂ and Nd, Gd:CaF₂ disordered crystals are grown by using temperature gradient technique (TGT). Among 0.5 at.%Nd, x at.%Gd(x=2, 5, 8, 10):CaF₂ crystals, the crystal with Gd³⁺ of 2 at.% has the longest fluorescence lifetime (499 μs). Increasing the concentration of Gd³⁺ up to 5 at.%, the crystal has a maximum absorption cross section of 1.9×10^-20 cm², and a maximum emission cross section of 1.9×10^-20cm². The crystal with Gd³⁺ of 8 at.%has a maximum emission bandwidth of 29.03 nm(FWHM). Among 0.6 at.%Nd, x at.%Y(x=2, 5, 8, 10):CaF₂ crystal, the crystal with Y³⁺ of 5 at.%has the biggest absorption cross section (2.41×10^-20 cm²), and the biggest emission cross section (3.17×10^-20 cm²), when the concentration of Y³⁺ is 5 at.%. When the Y³⁺ concentration increases up to 10 at.%, the crystal has a longest fluorescence lifetime of 359.4 μs and maximal emission bandwidth of 26 nm(FWHM).The different concentrations of codoping ions have different effects on the Nd:CaF₂ crystals, for the formations of different optical centers. In order to study the effects of local structure around Nd³⁺ on the optical properties in a set of Nd:CaF₂ single crystals with different codoping concentrations of Gd³⁺ and Y³⁺, the unit cell parameters are investigated by X-ray diffraction. With different concentrations of Gd³⁺ and Y³⁺ ions in Nd:CaF₂ crystal, the local structure of Nd³⁺ changes, which leads to different optical properties. The relevant details will further be explained in this paper.