Investigation of Absorption Spectra of (Cr4+,Yb3+):YAG Crystal

The absorption spectra characters of the (Cr,Yb):YAG,Cr:YAG and Yb:YAG crystals are reported. In the absorption spectra of the (Cr,Yb): YAG crystal,there are two absorption bands at 937 nm and 968 nm respectively,which are suitable for InGaAs diode laser pumping;and there is an absorption band of Cr4+ near 1030 nm,which is suitable for passive Q switch laser output at 1.03 μm. This Cr-Yb-codoped crystal may be a potential material for compact,diode laser pumped passive Q-switched solid-state laser with efficient,high-stable.     

Study of the effects of Cr ions on Yb in Cr,Yb:YAG crystal

The absorption and fluorescence spectra of Cr,Yb:YAG crystal were measured. There are two absorption bands at 940 nm and 968 nm although the absorption coefficient is lower than that of the absorption peak of Yb:YAG superimposed in Cr:YAG absorption peak. The emission peak intensity is 4 times lower than that of Yb:YAG, which may be caused by the existence of the ground state absorption of Cr⁴⁺ which quenches the Yb³⁺ emission intensity. Although the emission peak of Cr,Yb:YAG is lower than that of Yb:YAG, there is an advantage of this crystal which combines the saturable absorber and gain medium into one and can be a self-Q switching laser crystal if Cr,Yb:YAG crystal is pumped with high energy power.     

YAG晶体中Cr4+和Yb3+的光谱和荧光特性研究

报道了（Ｃｒ＾４＋,Ｙｂ＾３＋）：ＹＡＧ晶体的吸收光谱和荧光光谱特性。在室温下,（Ｃｒ＾４＋,Ｙｂ＾３＋）：ＹＡＧ晶体在９３７ｎｍ和９６８ｎｍ处存在两个吸收带,能与ＩｎＧａＡｓ激光二级管有效耦合：而且在１０３０ｎｍ处有一Ｃｒ＾４＋吸收峰,可以实现对Ｙｂ＾３＋的自调Ｑ激光输出。（Ｃｒ＾＋,Ｙｂ＾３＋）：ＹＡＧ 荧光光谱与Ｙｂ＾３＋：ＹＡＧ晶体一样,发光中心也是位于１０２９ｎｍ,但其强度比Ｙｂ＾３＋：     

Investigation of Absorption Spectra of(Cr~(4 ),Yb~(3 )):YAG Crystal

1lntroductionThsaturableabsotherswhichhavebeensucceSSfullyusedforpassiveQswitched1asersincludedye['],Lffi:F2colDcenterCrytals['],Cr -doPedcrysds['~'],etc.Amngthem,Cr -doPedCryStalsdevtheedinrecentyearssuchasCr :YAG,Cr :GSGG,andCr :WeSnyandsoon,havetheadVanageSofgoodphoto-chedcalandthermalstabillty,largabsorptbocross-section,besaturableintensityandhighdaInaethreshod.Inaddition,Cr canbedoPedintOgainmediumtoformselfQ-switchedl..,['J.Cr -dopedcrystalsbecomethemostprotalsingsatIJrable…     

不同Yb掺杂量的Yb:Y3Al5O12晶体的光谱分析

采用提拉法生长了Yb³⁺掺杂量分别为5.4at%, 16.3at%, 27.1at%, 53.6at%和100at%的Yb:Y₃Al₅O₁₂晶体.系统地表征和分析了Yb³⁺掺杂量对晶体吸收光谱和荧光光谱的影响.随着Yb³⁺掺杂量的增加，各峰值吸收系数呈线性增加的趋势.应用Smakula公式计算了各吸收峰对应的振荡强度，并分析了Yb³⁺掺杂量对振荡强度的影 关键词： 吸收光谱 荧光光谱 自吸收 浓度猝灭     

Investigation of the Emission Cross-sections and the Spectra of (Cr4+, Yb3+): YAG Crystal

The emission and the lifetime data of Cr, Yb: YAG and Yb: YAG were reported. The effective peak stimulated-emission cross section of chromium and ytterbium-co-doped yttrium-aluminum garnets (Cr, Yb: YAG) has been determined to be 8.98 × 10-20 cm2 at room temperature. The luminescence spectrum of Cr, Yb: YAG is the same as that of Yb: YAG. The luminescence lifetime of Cr, Yb: YAG at room temperature is 0.3 ms (Yb: YAG, 1.48 ms ). The causes of the differences in the fluorescence spectra and the stimulated emission cross-section between Yb: YAG and Cr, Yb: YAG crystals were discussed. Also the potential of Cr, Yb: YAG as a self Q- switched laser crystal was discussed.     

Yb:YAG晶体的光谱性能

系统地研究了不同掺杂浓度的Ｙｂ：ＹＡＧ晶体的光谱特性,通过吸收光谱的测量计算了晶体的吸收截面,用对易法计算了晶体的发射截面。在Ｙｂ：ＹＡＧ晶体毛坯中发现Ｙｂ＾２＋和色心,其浓度随Ｙｂ：ＹＡＧ晶体中Ｙｂ＾３＋的增加而增加。经１４００℃氧气氛退火后消失。首次用光子激发和Ｘ射线激发研究了Ｙｂ：ＹＡＧ晶体的荧光特性。     

Yb∶YAG晶体的荧光特性研究

测量了不同掺杂浓度Yb∶YAG晶体氧化和还原气氛退火前后的色心吸收光谱、荧光光谱和荧光寿命.研究了色心对Yb∶YAG晶体的荧光强度和荧光寿命的影响.结果表明,只有当Yb的掺杂浓度大于10 at.%时,色心吸收的加强对发光强度和荧光寿命有明显猝灭作用.     

Effect of ytterbium concentration on cw Yb:YAG microchip laser performance at ambient temperature – Part I: Experiments

The microchip laser performance of Yb:YAG crystals doped with different ytterbium concentrations (C_Yb=10, 15, and 20 at. %) has been investigated at ambient temperature without active cooling of the gain media. Efficient laser oscillation for a 1-mm-thick YAG doped with 10 at. % Yb³⁺ ions was achieved at 1030 and 1049 nm with slope efficiencies of 85% and 81%, correspondingly. The laser performance of heavy-doped Yb:YAG crystals was limited by the thermal population at terminated lasing level and thermal lens effect at room temperature without sufficient cooling of the samples. The laser emitting spectra of Yb:YAG microchip lasers with different Yb concentrations and output couplings are addressed with the local temperature rise, due to the absorption of the pump power inside the gain media under different pump levels. PACS 42.55.Xi; 42.70.Hj; 42.55.Rz     

Yb,Na:PbF(2): a potential new high-power laser material

Yb:PbF(2) and Yb,Na:PbF(2) laser crystals are grown by the Bridgman method. Room-temperature absorption, photoluminescence spectra, and fluorescence lifetimes of Yb(3+) ions in the crystals have been investigated. Experimental results show that Na(+) ions codoping with Yb(3+) as charge compensators can suppress the deoxidization of Yb(3+) to Yb(2+). The result of diode-pumped laser operation of a Yb,Na:PbF(2) single crystal is reported for the first time to the best of our knowledge . With a 1mol.%Yb(3+)-doped sample, we obtained 2.37W output power at 1056nm for 17.9W of incident power at 978nm.     

Influence of Gamma-Ray Irradiation on Absorption and Fluorescent Spectra of Nd：YAG and Yb：YAG Laser Crystals

We investigate the influence of gamma-ray irradiation on the absorption and fluorescent spectra of Nd^3＋：Y3A15 O12 （Nd： YAG） and Yb^3＋ ： Y3A15 O12 （Yb： YAG） crystals grown by the Czochralski method. Two additional absorption （AA） bands induced by gamma-ray irradiation appear at 255nm and 340nm. The former is contributed due to Fe^3＋ impurity, the latter is due to Fe^2＋ ions and F-type colour centres. The intensity of the excitation and emission spectra as well as the fluorescent lifetime of Nd：YAG crystal decrease after the irradiation of 100 Mrad gamma-ray. In contrast, the same dose irradiation does not impair the fluorescent properties of Yb：YAG crystal. These results indicate that Yb： YA G crystal possesses the advantage over Nd： YA G crystal that has better reliability for applications in harsh radiant environment.     

Annealing effect on Cr,Yb:YAG laser crystal

The absorption spectra, fluorescence spectra, and lifetimes of as-grown and annealed Cr,Yb:YAG crystal grown by Czochralski technique have been measured. The broad absorption bands in the visible region increase in intensity and shift to long wavelength after annealing, and the additional absorption around 482 nm may be possibly due to new octahedral Cr4+ center in the crystal, and the increase in the infrared (IR) region is due to the increase of Cra+. The increase of Cr4+ also results in the groud state absorption and the concentration quenching of Ybs+ in Cr,Yb:YAG crystal after annealing, the fluorescence intensity is reduced to 75% and the emission lifetime is shortened from 1.40 to 0.44 ms.     

The effect of temperature on absorption in end-pumped Yb:YAG thin disk lasers

In this paper, the dependence of the absorbed power on the temperature in an end-pumped CW quasi-three-level Yb:YAG thin disk laser is calculated. Here, we have used the temperature-dependent form of the Boltzmann occupation factors, absorption cross-section and thermal conductivity of the Yb:YAG crystal. A Monte Carlo ray tracing code and a 2D finite element analysis (FEA) with the ANSYS package have been used to calculate the absorbed power and the temperature distribution inside the Yb:YAG thin disk laser, respectively. According to the model, the temperature-dependent absorbed power turns out to be 18% less than the temperature-independent absorbed power in the top center of the Yb:YAG thin disk laser for used parameters.     

Yb：YAG晶体中的荧光浓度猝灭现象

在Ｙｂ：ＹＡＧ晶体中发现浓度猝灭现象,对猝灭机制进行了分析研究,指出退火前晶体的荧光浓度猝灭现象主要由Ｙｂ＾２＋、色心和由此产生的晶格畸变所致高掺杂浓度时痕量稀土杂质离子的存在也将导致浓度猝灭,确定了Ｙｂ：ＹＡＧ晶体中Ｙｂ＾３＋的理想掺杂浓度。     

Yb:FAP和Yb:C_3S_2-FAP晶体光谱的温度特性和选择激发

报导了Yb :FAP和Yb :C3S2 _FAP晶体在不同温度下的吸收光谱和荧光光谱实验结果 ,研究发现由于电子_声子近共振耦合作用 ,Yb :FAP和Yb :C3S2 _FAP晶体均存在有明显的振动谱 ,Yb :FAP晶体的零声子线在低温下还劈裂为相差 10cm- 1 的两条线 .采用激光选择激发技术研究了Yb3 离子在FAP和C3S2 _FAP晶体中的格位特征 ,结果表明Yb3 离子在这两种基质中都只占据Ca(Ⅱ )格位 ,但由于CaF2 的挥发 ,导致了Ca(Ⅱ )格位的局部畸变 .     

Yb:Y3Al5O12/Y3Al5O12复合晶体的制作和光谱性能

采用热键合技术,制作中运用不同的工艺参量制作出12片Yb:Y3Al5O12/Y3Al5O12(Yb:YAG/YAG)复合.晶体.利用偏光显微镜对其键合界面进行了观察,研究了样品的透射光谱,从而确定出复合晶体合适的制作工艺.通过透射光谱的形状和透射率来表征复合晶体键合界面的质量.研究表明Yb:YAG/YAG复合晶体键合质量较好,可实现一体化.     

Laser-diode pumped heavy-doped Yb:YAG ceramic lasers

Laser performance of heavy-doped Yb:YAG ceramics was investigated using a two-pass pumping miniature laser configuration. Slope efficiency of 52% and optical-to-optical efficiency of 48% have been achieved for 1-mm-thick YAG ceramic doped with 20 at.% ytterbium ions. Laser spectra of Yb:YAG ceramic and single-crystal lasers were addressed under different intracavity laser intensities. Heavy-doped Yb:YAG ceramic is more suitable for a thin disk laser than a single-crystal with the same Yb(3+)-ion lasants.     

Yb :YAG晶体的闪烁特性

通过不同Yb³⁺掺杂浓度(5%~30%,原子数分数)的Yb:YAG晶体的阴极射线发光谱、衰减时间、光输出及其温度依赖关系的测量,研究了Yb:YAG晶体的闪烁性能.不同Yb³⁺掺杂浓度的Yb:YAG晶体具有不同的光输出和猝灭温度,光输出随Yb³⁺掺杂浓度的增大而降低,猝灭温度则随掺杂浓度的增大而升高.室温下Yb:YAG晶体的发光衰减时间较短,均小于50ns.Yb³⁺掺杂浓度为5%的Yb:YAG晶体具有较高的光输出和较低的猝灭温度.     

Yb3+离子掺杂浓度对Yb∶YAG晶体发光及荧光寿命的影响

研究了不同掺杂浓度Yb∶YAG晶体的发光特性和荧光寿命.Yb3+在YAG晶体中的掺杂浓度分别为5at%、10at%、20at%、30at%.Yb3+离子掺杂浓度越高，Yb∶YAG晶体的吸收系数越大.采用940 nm波长的LD泵浦源和TRIA X550荧光谱仪，对这一系列掺有不同浓度Yb3+的Yb∶YAG晶体进行了荧光光谱的测定.结果表明:在1030 nm主发光波段的荧光强度以10at%Yb∶YAG的为最强.同时发现它在450 nm-680 nm波段有明显的可见发光，其强度随Yb3+掺杂浓度的增加而迅速地增强.Yb∶YAG晶体的荧光寿命存在浓度猝灭现象，对猝灭机制进行了分析研究，指出浓度猝灭的主要原因是合作发光和痕量稀土离子的上转换发光.     

Yb：YAG晶体中的色心

在用引上法生长的Ｙｂ：ＹＡＧ晶体中，存在一个独特的色心，其吸收带位于３７５ｎｍ的６２５ｎｍ，随着Ｙｂ２Ｏ３掺杂浓度的增加，色心浓度增加，探讨了晶体生长过程中色心形成机理。高强γ射线辐照Ｙｂ：ＹＡＧ晶体，诱导大量色心的形成。晶体中的 对激发态Ｙｂ＾３＋离子的荧光寿命具有流淬火效应，因此，Ｙｂ：ＹＡＧ激光晶体需要经高温退火，消除色心的影响。