用坩埚下降法生长了Tm3+掺杂浓度分别为0.8%和1.3%的优质大尺寸LiYF4(LYF)单晶体。测定了单晶体的吸收光谱、发射光谱, 并计算了3F4能级的的最大吸收截面与最大发射截面分别为0.25×10-20 cm2和0.33×10-20 cm2。以796 nm半导体激光器(LD)为泵浦源, 采用短平板腔结构模型研究了Tm掺杂LYF单晶体在~2.0 μm波段的激光输出性能。当LD泵浦功率为3.4 W时, Tm∶YLF晶体的最大激光输出功率为1.88 W, 相应的光光转换效率和斜率效率分别为51%和57%。使用半导体可饱和吸收镜抽运Tm掺杂LYF单晶体, 测试其在~2.0 μm波段连续波锁模激光运转。当最大抽运功率为3.5 W时, 获得锁模激光的最大平均输出功率为200 mW, 此时锁模脉冲宽度~20 ps, 对应的重复频率63.86 MHz, 中心谱线为1.88 μm。结果表明, Tm掺杂LYF单晶体是一种具有较好物理性能的~2 μm波段超快激光晶体。

应用坩埚下降法生长了Pr3+离子掺杂的Na5Lu9F32单晶体.系统地研究了Pr3+掺杂的Na5Lu9F32单晶的吸收光谱、荧光光谱和荧光衰减曲线.应用Judd-Ofelt理论分析计算了其光学强度等参数, 结果表明Pr3+离子处于Pr-F强共价键的高对称环境中.在440 nm光的激发下观察到以482、523和605 nm为中心的尖锐的强荧光发射带.研究了Pr3+掺杂浓度对上述发光强度的影响规律, 实验发现当Pr3+掺杂浓度达到~0.5 mol%时, 其荧光发射强度达到最大.分析了环境温度从298 K到443 K变化时对荧光强度的影响, 随着温度的增加, 荧光强度逐步变弱, 且其523 nm的绿光受温度影响要小于482 nm的蓝光和605 nm的红光.

High-quality KMgF3 single crystal containing 0.5 mol% europium (Eu) was prepared by an improved Bridgman method. X-ray diffraction (XRD), photoluminescence spectra and fluorescence lifetime were measured. The results in-dicate the reduction of Eu3+ to Eu2+ in the KMgF3 single crystal. Under the excitation of 259 nm, 370 nm and 394 nm, the sample has two distinct emissions of Eu2+:4f7→4f7(~363 nm) and 4f65d1→4f7 (~440 nm). The substitution site for Eu ion is confirmed. The optical property investigation result shows that the Eu2+ doped KMgF3 single crystal may be used as potential laser media and related materials for optical devices.

The growth of Na5Lu9F32 single crystals doped with Cr3+ ions in 0.1 mol%, 0.2 mol% and 0.5 mol% concentrations by Bridgman method was reported. The optical absorption and luminescence spectra decisively demonstrate that the Cr dopant enters Na5Lu9F32 as Cr3+. Fluorescence emission at wavelengths of 418 nm, 444 nm, 653 nm and 678 nm can be observed under the excitation of 372 nm and the fluorescence lifetime at 418 nm was measured to be ~10.31 μs. The possible crystal sites for Cr3+ ions in Na5Lu9F32 single crystal were discussed, and the lattice parameter Dq, Racach parameters B and C were estimated.

Tm3+ doped Na5Lu9F32 single crystal with high optical quality was grown by an improved Bridgman method. The Judd-Ofelt intensity parameters Ωt (t=2, 4, 6) were calculated according to the measured absorption spectra and physical-chemical properties of the obtained Na5Lu9F32 single crystal. The stimulated emission cross-section of the 3F4→3H6 transition (~1.8 μm) is 0.35×10-20 cm2 for Tm3+ doped Na5Lu9F32 single crystal. The emission spectra under the excitation of 790 nm laser diode (LD) and fluorescence lifetime at 1.8 μm were measured to reveal the fluorescence properties of Tm3+ doped Na5Lu9F32 single crystal. The research results show that the Tm3+ doped Na5Lu9F32 single crystal has larger stimulated emission cross-section compared with other crystals. All these spectral properties suggest that this kind of Tm3+doped Na5Lu9F32 crystal with high physical-chemical stability and high-efficiency emission at 1.8 μm may be used as potential laser materials for optical devices.

采用改进过的布里奇曼法成功地生长了Tm3+离子浓度从0.5～4 mol%变化的高质量Na5Lu9F32单晶.在790 nm LD激发下, 研究了不同Tm3+掺杂晶体在1.86 μm波段的荧光发射性能、衰减曲线以及Tm3+离子之间的能量传递过程.当Tm3+离子掺杂浓度增加到~1.95 mol%时, 晶体在1.86 μm处的荧光发射强度达到最大.然后, 随着Tm3+离子浓度进一步的增大, 发射强度迅速下降.然而, Tm3+离子在3F4能级处的荧光寿命随着Tm3+掺杂浓度从0.5增加到4 mol%, 逐渐降低.同时计算了1.86 μm处最大的受激发射截面为0.80×10－20 cm2.Tm3+离子的浓度猝灭效应和离子之间的交叉弛豫能量传递过程是造成1.86 μm荧光发射变化的主要原因.

Tm³⁺doped Na₅Lu₉F₃₂single crystal with high optical quality was grown by an improved Bridgman method. The Judd-Ofelt intensity parameters Ω_t(t=2, 4, 6) were calculated according to the measured absorption spectra and physical- chemical properties of the obtained Na₅Lu₉F₃₂single crystal. The stimulated emission cross-section of the ³F₄→³H₆transition (~1.8 μm) is 0.35×10^-20cm²for Tm³⁺doped Na₅Lu₉F₃₂single crystal. The emission spectra under the excitation of 790 nm laser diode (LD) and fluorescence lifetime at 1.8 μm were measured to reveal the fluorescence properties of Tm³⁺doped Na₅Lu₉F₃₂single crystal. The research results show that the Tm³⁺doped Na₅Lu₉F₃₂single crystal has larger stimulated emission cross-section compared with other crystals. All these spectral properties suggest that this kind of Tm³⁺doped Na₅Lu₉F₃₂crystal with high physical-chemical stability and high-efficiency emission at 1.8 μm may be used as potential laser materials for optical devices.

The Ho³⁺/Pr³⁺co-doped NaYF₄single crystals with various Pr³⁺concentrations and constant Ho³⁺molar percentage of ~1% were grown by an improved Bridgman method. Compared with the Ho³⁺single-doped NaYF₄crystal, an obviously enhanced emission band at 2.85 μm is observed under 640 nm excitation. The Judd-Ofelt strength parameters (Ω₂, Ω₄and Ω₆) are calculated, the radiative transition probabilities (A), the fluorescence branching ratios (β) and the radiative lifetime (τrad) are obtained in the meantime. The energy transfer from Pr³⁺to Ho³⁺and the optimum fluorescence emission of Ho³⁺ions around 2.85 μm are investigated. Moreover, the maximum emission cross section of above samples at 2.85 μm is calculated to be 0.72×10^-20cm²for the NaYF₄single crystal with Ho³⁺molar percentage of 1% and Pr³⁺molar percentage of 0.5% according to the measured absorption spectrum. All results suggest that the Ho³⁺/Pr³⁺co-doped NaYF₄single crystal may have potential applications in mid-infrared lasers.

采用坩埚下降法成功地生长了Er3+离子掺杂的Na5Lu9F32(NLF)单晶体。测定了单晶体在400～2 500 nm波段的吸收光谱与2.5～25 μm红外波段的透过光谱。Na5Lu9F32单晶体在400～7 150 nm宽波段范围具有好的光学透过性, 在该波段的透过率达到90%。在透过光谱中几乎观察不到2.7 μm中红外波段的吸收, 说明单晶体中OH-离子的含量极低。根据测定的吸收光谱, 通过Judd-Ofelt理论计算了Er3+在单晶体中的光学强度参数Ωt(Ω2=2.08,Ω4=2.07,Ω6=0.75), 以及相应的辐射跃迁速率、荧光分支比和荧光寿命。根据Futchbauer-Ladenburg公式估算了样品的发射截面大约分别为1.42×10-20 cm2(4I13/2→4I15/2)和1.66×10-20 cm2(4I11/2→4I13/2)。在980 nm半导体激光器(LD)激发下, 研究了单晶体的近红外1.5 μm与中红外2.7 μm的发射光谱特性。

采用坩埚下降法生长出Ho3+离子掺杂浓度~1.90 mol%、Tm3+不同掺杂离子浓度(0.99 mol%, 1.58 mol%, 2.37 mol%, 3.16 mol%, 3.99 mol%, 7.19 mol%)的双掺杂立方晶相NaYF4单晶体.根据测定的吸收光谱以及800 nmLD波长激发下的发射光谱、发射截面和衰减曲线, 研究从Tm3+离子到Ho3+离子的能量传递机制、Tm3+离子的浓度猝灭效应和Ho3+离子在2.04 μm波段的优化发光效应.当Ho3+离子浓度保持为~1.90 mol%不变, Tm3+离子浓度从0.99 mol% 增加到 1.59 mol%时, 2.04 μm波段的发射强度逐步增强；当浓度从1.59mol% 增加到7.19mol%时, 发射强度逐步减弱.Ho3+(1.90 mol%)/Tm3+(1.59 mol%)共掺的单晶体的发射截面最大, 达到2.17×10－20 cm2, 其荧光寿命最长, 为21.72 ms；同时, 根据Ho3+离子的吸收截面和Tm3+离子的发射截面, 计算得到该样品从Tm3+∶3F4→Ho3+∶5I7稀土离子能量传递系数和Ho3+∶5I7→Tm3+∶3F4反传递系数分别为CTm-Ho=24.14×10－40 cm6/s, CHo-Tm=2.05×10－40 cm6/s.