新型Nd3+∶Ca4GdO(BO3)3自倍频晶体Cr4+∶YAG被动调Q激光特性研究

采用氙灯抽运自倍频晶体Nd3 +∶Ca4GdO(BO3 ) 3 (简称Nd∶GdCOB) ,Cr4+∶YAG被动调Q ,实现了Nd∶GdCOB晶体被动调Q激光运转 ,测量了饱和吸收体Cr4+∶YAG不同小信号透过率下绿激光单脉冲的输出能量、脉冲宽度、重复率 ,给出了描述Nd∶GdCOB晶体调Q工作原理的耦合波方程组 ,数值求解了该方程组 ,所得的理论结果与实验值相符合     

三硼酸铋晶体及其高温熔体结构的拉曼光谱研究

测量了BiB3O6晶体从常温到熔融态的拉曼光谱,考察了其温致结构变化和预测了熔体的结构基元。同时,采用量子化学从头计算和密度泛函理论对拉曼光谱进行了计算和结构分析。结果表明,随着温度的升高,对包含阳离子Bi的外部晶格和[BO3]3-硼氧三角形基团结构的温致结构影响有限,却有效地削弱了[BO4]5-硼氧四面体基团结构,其松弛度增加,稳定性变差,并在熔体结构中彻底消失。研究表明BiB3O6熔体主要以硼氧六元环[B6O12]6-的形式存在,阳离子Bi起电荷平衡作用,其氧配位数为3,有别于晶体中的6。     

新型Nd^3＋：Ca4GdO（BO3）3自倍频晶体Cr^4＋：YAG被动调Q激光特性研究

采用氙灯抽运自倍频晶体Nd^3 :Ga4GdO(BO3）3（简称Nd:GdCOB)，Cr^4 :YAG被动调Q，实现了Nd:GdCOB晶体被动调Q激光运转，测量了饱和吸收体Cr^4 :YAG不同小信号透过率小绿激光单脉冲的输出能量、脉冲宽度、重复率，给出了描述Nd:GdCOB晶体调Q工作原理的耦合波方程组，数值求解了该方程组，所得的理论结果与实验值相符合。     

三硼酸钾的合成、表征及其振动光谱的研究

借助自行设计的沸腾反应器,采用碳酸钾和硼酸通过控制适宜的原料配比、反应温度和脱水温度合成出三硼酸钾。通过化学分析确定合成物分子式为一水三硼酸钾(KB₃O₅·H₂O),通过粉末X射线衍射光谱(XRD)、傅里叶变换红外光谱(FTIR)、拉曼光谱(Raman)和热重分析(TG)等手段对其进行了表征,由粉末X射线衍射光谱分析确定合成物物质形态为无定形态,由傅里叶变换红外光谱和拉曼光谱分析确定合成物分子中存在三配位硼氧键B₍₃₎—O、四配位硼氧键B₍₄₎—O、羟基及三硼酸根离子,由热重分析确定合成物分子中存在能够失去一分子水的基团,并推出合成物三硼酸钾的结构式为K[B₃O₄(OH)₂]。研究了合成物的振动光谱,包括红外光谱和拉曼光谱,考察了其中硼原子的主要存在形式三配位硼氧键B₍₃₎—O和四配位硼氧键B₍₄₎—O以及其他基团的振动情况,对振动频率进行了归属。     

激光自倍频晶体研究和应用进展

激光自倍频晶体是一类同时具有激光和非线性效应的复合功能晶体。以激光自倍频晶体制作的全固态激光器具有体积小,调整方便,稳定性高等优点。自1970年代以来,以LiNbO3,YAl3(BO3)4倍频晶体为基质的激光自倍频晶体实现了自倍频激光运转。近年来,以RECa4O(BO3)3(RECOB)为基质的激光自倍频晶体受到重视和广泛研究。本文从对激光晶体、非线性光学晶体及激光自倍频晶体的基本要求出发,在综述激光自倍频晶体研究历史的基础上,讨论了激光自倍频晶体中的基波和倍频光,探讨了NYAB和Nd:GdCOB一类晶体中晶体长度,Nd3+浓度和效率之间的关系。理论估算表明,当浓度适当,晶体长度10mm时,这两类晶体的光–光转换效率可达30%以上。本文总结了NYAB系列晶体的研究历程及RECOB系列激光自倍频研究的思路及取得的成果。在最近10年中,利用山东大学生长的Yb:YAB晶体,获得1.1 W自倍频绿光,光光转换效率为10%;在RECOB体系中,比较了各种晶体的特点,选定Nd:GdCOB为主要研究对象,经过晶体掺钕浓度和长度关系,位相匹配方向、膜系及热工程等多方面研究,获得了1.36 W的545 nm绿光输出,光–光转换效率为17.1%;输出功率为1.03 W时,半小时功率波动不超过1%。这是目前为止,Nd3+离子激光自倍频晶体的最好结果。文章最后介绍了激光自倍频晶体的可能应用。通过理论和实验分析,认为到目前为止Nd:GdCOB是以Nd3+为激活离子最后的激光自倍频晶体,而在Yb3+为激活离子时,Yb:YAB晶体最佳。     

Nd:GdCOB晶体1331.0 nm基频光运转和自倍频红光的观察

Nd:Ca4GdO(BO3)3(简称Nd:GdCOB)是一种新型自倍频晶体[1]. 利用该晶体实现1060.0 nm的自倍频绿光输出, 因内外均已有报道[2]. 我们利用Datachrom-5000型染料激光器泵浦该晶体成功地实现了1331.0 nm基频光和665.5 nm自倍频红光的输出.     

无水五硼酸钾晶体高温性质振动光谱的研究

利用自行设计的反应器研究了高温条件下水蒸汽对无水五硼酸钾晶体结构的影响,借助于X射线衍射、红外光谱、Raman光谱等手段分析了无水五硼酸钾晶体高温性质的振动光谱。在水蒸汽的作用下,五硼酸钾的B₂O₃/K₂O(摩尔比)变小,X射线衍射分析表明750 ℃时晶体中有K₅B₁₉O_<sub>31存在,而红外光谱与Raman光谱分析表明由于水蒸汽的作用使得晶体中的三角形B₍₃₎—O结构单元向四面体B₍₄₎—O结构单元转变,四面体的B₍₄₎—O含量增加并且硼氧网络结构被进一步打断。     

Bi4Ge3O12晶体及其掺杂晶体的拉曼光谱研究

利用拉曼光谱分别对Bi4 Ge3O12(BGO)晶体以及BGO:Pb(0.02 wt%),BGO:Al(0.02 wt%)进行了分析研究.测得的拉曼光谱显示,掺杂晶体对比纯的BGO晶体,在某些特征峰处,相对强度发生改变.此外,对于掺杂的晶体,部分拉曼特征峰会有偏移.因此,可以通过测定拉曼光谱来判定样品是否含有杂质.     

硼酸晶体结构分析及拉曼光谱测试

对硼酸(H3BO3/B(OH)3)粉末进行XRD测试,确定其空间结构和所属对称点群;对硼酸晶体进行晶格振动模式分析,确定其有18个拉曼活性模式4Ag+2E1g+5E2g;并对其进行50~3800cm-1波段的Raman散射测试,利用理论结果对谱图进行了讨论,确定了各振动峰的特性。     

三硼酸铯和硼酸铯锂晶体的晶格振动光谱研究

本文对新型非线性光学晶体三硼酸铯（ＣｓＢ３Ｏ５∶ＣＢＯ）和硼酸铯锂（ＣｓＬｉＢ６Ｏ１０∶ＣＬＢＯ）进行了晶格振动光谱研究。首先对两种晶体的基本晶格振动模进行了对称性分类,记录了两种晶体低温下的拉曼光谱和室温下的红外反射光谱,对晶体的晶格振动模进行了认定,将振动模归属于平面六元环（Ｂ３Ｏ６）和四面体（ＢＯ４）。然后比较了ＣＢＯ,ＣＬＢＯ和ＬＢＯ（ＬｉＢ３Ｏ５）三种晶体的晶格振动光谱,讨论了阳离子对振动光谱的影响。另外,还讨论了硼酸盐晶体晶格振动模ＬＯ ＴＯ分裂的大小与晶体非线性光学系数之间的关系。     

Formation of planar optical waveguides in the new nonlinear gadolinium calcium oxoborate, Ca(4)GdO(BO(3))(3), crystal by 2-MeV He(+) implantation

A planar waveguide composed of the new nonlinear material, Ca(4)GdO(BO(3))(3) (GdCOB), is reported. This crystal belongs to the calcium oxoborate family. It has attractive nonlinear properties that can be of great interest in integrated optics applications. We used a method of He(+) implantation to fabricate waveguides in GdCOB crystals by creating a buried layer of lowered refractive index a few micrometers beneath the surface. Both TE and TM modes were observed. Therefore, according to the Y cut of the crystal, refractive-index values of n(x) , n(y) , and n(z) were obtained. Index profiles were reconstructed by an improved inverse WKB method. The profiles showed a steplike index behavior, indicating that the guiding region obtained was of good optical quality.     

Electronic structure of gadolinium calcium oxoborate

Gadolinium calcium oxoborate (GdCOB) is a nonlinear optical material that belongs to the calcium-rare-earth (R) oxoborate family, with general composition Ca₄RO(BO₃)₃ (R³⁺ = La, Sm, Gd, Lu, Y). X-ray photoemission was applied to study the valence band electronic structure and surface chemistry of this material. High resolution photoemission measurements on the valence band electronic structure and Gd 3d and 4d, Ca 2p, B 1s and O 1s core lines were used to evaluate the surface and near surface chemistry. These results provide measurements of the valence band electronic structure and surface chemistry of this rare-earth oxoborate.     

Nonlinear optical properties of LaCa(4)O(BO(3))(3)

We have grown LaCa(4)O (BO(3))(3) (LaCOB), an isostructural member of GdCa(4)O(BO(3))(3) (GdCOB) family and characterized its nonlinear optical properties. At 1064nm, d(eff) of 0.52+/-0.05 pm /V and an angular sensitivity of 1224+/-184(cm rad)(-1) for type I frequency doubling in LaCOB were determined relative to those of KTiOPO(4) , beta-BaB(2)O(4) , KD(2)PO(4) , LiB(3)O(5) , YCa(4)O(BO(3))(3) (YCOB), and GdCOB. The d(alphabetabeta) and d(gammabetabeta) coefficients of the nonlinear optical tensor for LaCOB, GdCOB, and YCOB were determined to be equivalent within the experimental uncertainty and have values of ?0.26+/-0.04?pm/V and ?1.69+/-0.17?pm /V , respectively. From phase-matching angle measurements at 1064 and 1047nm, we predict that LaCOB is noncritically phase matched at 1042+/-1.5 nm .     

Dye-laser-pumped Nd:GdCOB Self-frequency-doubling Laser

Nd:Ca4GDO(BO3)3, abbreviated as Nd:GdCOB, is a new multifunctional material for self-frequency-doubling green lasers. By using datachroom-5000 pulsed dye-laser as pumping source, we have achieved green laser output at 530.2 nm from a Nd:GdCOB crystal (7 mol-% Nd3+) uncoated HT film for 1.06 μm and 0.53 μm. The threshold energy is lower than 1.2 mJ. When the pumping energy is 17.5 mJ, the output energy of the green laser is 1.35 mJ and the corresponding conversion efficiency is 7.7%.     

Assessment of gadolinium calcium oxoborate (GdCOB) for laser applications

Increasing demand for growing high quality laser crystals puts a question about their most important parameters that one should concentrate on to get a desired product which will exhibit best properties in practical use. And by no means, this is a simple question. Apart of the usual lasing properties associated with a special dopant in the host material itself, one needs to consider another two lasing phenomena, namely second (SHG) and higher harmonic generation, and self-frequency doubling (SFD). Not necessarily all of these three can meet altogether in the same host material to yield in its best appearance in every case. We have made a review of basic properties of gadolinium oxoborate GdCa₄O(BO₃)₃ (GdCOB) crystal and came to the conclusion that, currently, as a host material this is probably the best in all of its lasing applications. Although GdCOB has low thermal conductivity, which requires a suitable cooling, on the other hand it has got small thermo-optic coefficients which govern good operation in SHG and SFD experiments.     

Laser characteristics of Cr:Nd:GdCOB self-frequency-doubling crystal

The phase matching angle of GdCOB crystal is calculated. By using Xenon flash lamp as pump source, we have realized the free run from 1.06 μm to 0.53 μm in self-frequency-doubling Cr:Nd:GdCOB (bi-doped) crystal and Nd:GdCOB (uni-doped) crystal. The experimental results show that the threshold energies for bi-doped crystal and uni-doped crystal are 0.92 J and 1.00 J, respectively; when the pump energy is 10 J, the output energies of green laser for two kinds of crystals are 2.46 mJ and 1.96 mJ, respectively. The output energy of Cr:Nd:GdCOB crystal has an increase of 25% in comparison to that of Nd:Gd:COB crystal. In addition, we discuss ways to improve efficiency.     

磷酸钠结构的高温拉曼光谱研究

用高温拉曼光谱仪测定了固态和熔融态磷酸钠(Na3PO4)晶体的光谱,分析了磷酸钠晶体的结构及其随温度的变化。通过对从常温谱到高温谱的解析,得出主峰波数随温度的变化及主峰半高宽的变化,可以观察到在600 K附近及1773 K有两个相变产生。此外,磷酸钠晶体的相关高温DSC检测分析,也和拉曼谱中发现的两个相变符合。量子化学理论计算同时对该体系的P-O键振动和平均键长进行了模拟,随着键长的增加,对应的振动频率会降低。还确认了磷酸钠Raman光谱中各个峰的归属,938 cm-1波数处的峰属于(PO4)3-中P-O键的对称伸缩振动,是Na3PO4的特征峰,425及580 cm-1处峰属于磷氧四面体的弯曲振动。     

一水柠檬酸单晶的激光拉曼光谱

本文报道了一水柠檬酸在不同几何配置下的拉曼光谱。从一些谱峰的位移,各向异性及退偏振可以判断,晶体分子中存在较强的氢键。由CC,CO,CO谱线的频移等实验结果可以判断,由于氢键的影响,分子间的耦合及众多COO