Crystal growth, structure, optical properties and laser performance of new tungstate Yb:Na2La4(WO4)7 crystals
Crystal growth, structure, optical properties and laser performance of new tungstate Yb:Na2La4(WO4)7 crystals
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新型钨酸盐Yb:Na2La4(WO4)7晶体的晶体生长、结构、光学性质和激光性能
DOI：
10.1016/j.optmat.2020.110653
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发表时间：
2020-11
影响因子：
3.9
通讯作者：
Yeqing Wang
中科院分区：
文献类型：
--
作者：
Yi Yu;Shimin Wu;Xiurong Zhu;Xianke Zhang;Huajun Yu;Huilin Qiu;Yeqing Wang
摘要2at.%和10at.%之间变化采用提拉法生长了尺寸分别为1.21 × 24 mm 3和1.24 × 28 mm 3的Yb：Na 2La 4（WO 4）7晶体。研究了两种晶体的生长、光谱性质和激光性能。2at.%的吸收峰截面和10at.%之间变化Yb：Na 2La 4（WO 4）7晶体的σ极化率分别为1.51× 10− 20 cm 2和1.74× 10− 20 cm 2，π极化率分别为1.61× 10− 20 cm 2和1.34× 10− 20 cm 2。用Füchtbauer-Ladenburg（FL）方法计算了两种晶体在1012 nm处沿着σ取向的发射截面分别为1.45× 10− 20 cm 2和2.31× 10− 20 cm 2。采用倒易法（RM）计算了两种晶体在1012 nm处的发射截面，其值分别为0.27× 10− 20 cm 2和0.34× 10− 20 cm 2。晶体中存在较强的再吸收效应，对再吸收几率的分析表明，当Yb 3+浓度高达10at%Yb3+时，晶体中的再吸收效应比其它掺Yb晶体中的再吸收效应更严重。测量了两种晶体中Yb 3+的激发态寿命，拟合值分别为0.392ms和0.42 2 ms。根据吸收光谱和发射光谱，计算了Yb：Na 2La 4（WO 4）7的最小反转分数β min、饱和泵浦强度Isat、最小泵浦强度Imin和增益发射截面等重要激光势参数，结果表明Yb：Na 2La 4（WO 4）7是一种候选的激光介质。激光实验也进行了和连续波（cw）激光的行动证明与c切未涂层的晶体样品在平凹腔，端面泵浦的977 nm的激光二极管。在2at.%的情况下，最大输出功率分别为1.15W和0.85W和10at.%之间变化Yb：Na 2La 4（WO 4）7晶体，当输出耦合器的透过率为5%时，其斜率效率分别为17.24%和12.35%，沿着增大。结果表明，新型钨酸盐Yb：Na 2La 4（WO 4）7晶体是一种良好的激光介质。
Abstract The 2 at.% and 10 at.% Yb: Na 2 La 4 (WO 4) 7 crystals with dimensions of Ø 21× 24 mm 3 and Ø 24× 28 mm 3 were grown by the Czochralski method. The crystal growth, spectroscopic properties and laser performances of the two crystals were investigated. The peak absorption cross-sections of the 2 at.% and 10 at.% Yb: Na 2 La 4 (WO 4) 7 crystals are 1.51× 10− 20 cm 2 and 1.74× 10− 20 cm 2 along σ-polarization, as well as 1.61× 10− 20 cm 2 and 1.34× 10− 20 cm 2 along π-polarization, respectively. The emission cross sections calculated by Füchtbauer-Ladenburg (FL) method along σ-orientation are 1.45× 10− 20 cm 2 and 2.31× 10− 20 cm 2 at 1012 nm for the two crystals, respectively. The reciprocity method (RM) was adopted to calculate the emission cross-sections for compassion, and the values at 1012 nm for the two crystals are 0.27× 10− 20 cm 2 and 0.34× 10− 20 cm 2, respectively. Strong re-absorption effect exists in the crystals, and the analysis of the re-absorption probabilities shows that the crystal with as high as 10 at% Yb 3+ concentration has more serious re-absorption effect than many other Yb-doped crystals. The lifetimes of the excited state of Yb 3+ in the two crystals were measured and fitted to be 0.392 ms and 0.422 ms, respectively. Based on the absorption and emission spectra, the important laser potential parameters, including the minimum inversion fraction β min, the saturation pump intensity I sat, the minimum pump intensity I min and gain emission cross-sections were evaluated and results indicates that Yb: Na 2 La 4 (WO 4) 7 are candidate lasing mediums. The laser experiments were also performed and continuous-wave (cw) laser actions were demonstrated with the c-cut uncoated crystal samples in a plane-concave cavity, end pumped by a 977 nm laser diode. The maximum output powers are respectively 1.15 W and 0.85 W for the 2 at.% and 10 at.% Yb: Na 2 La 4 (WO 4) 7 crystals, along with the corresponding slope efficiencies of 17.24% and 12.35% when the transmittance of the output coupler is 5%. All the results indicate that the new tungstate Yb: Na 2 La 4 (WO 4) 7 crystal is a good laser medium.