无序Nd:CNGG晶体的生长及激光性能研究

本文报道了无序晶体Nd:CNGG的生长及其激光性能.采用提拉法成功生长了绿色、透明的大尺寸Nd:CNGG晶体.在He-Ne激光器照射下,未发现散射颗粒.在半导体激光器泵浦的条件下,我们研究了其1.06μm的连续激光输出性能.在8.56 W泵浦的情况下,得到1.52 W的激光输出.     

Nd∶GdxLa1-xVO4 (x=0.8、0.6、0.45)晶体的制备和性能研究

报道了Nd∶GdxLa1-xVO4 (x=0.8、0.6、0.45)系列新型晶体的生长,并研究了它们的性能. 用中频感应提拉法生长了Nd∶GdxLa1-xVO4 (x=0.8、0.6、0.45)系列晶体.研究表明,随着La在晶体中含量的增加,晶体生长的难度逐渐增大. 测量了这三种晶体的结构和晶胞参数, 结果表明它们的结构仍为锆英石结构,随着La掺杂量的增加,晶胞参数逐渐变大. 测量了Nd∶Gd0.8La0.2VO4和Nd∶Gd0.6La0.4VO4晶体的吸收谱和荧光谱.随着La掺杂量的增加,在808.5 nm附近的吸收半宽增加.其发射波长没有明显的变化. 用LD抽运Nd∶Gd0.8La0.2VO4晶体,进行了发射波长为1.06 μm和1.34 μm的激光实验.在2.9 W的抽运功率下,获得了1.18 W的1.06 μm和671 mW的1.34 μm的激光输出(OC27)     

Watt-level continuous-wave and passively Q-switched red lasers pumped by a single blue laser diode

Praseodymium-ion-doped gain materials have the superiority of lasing at various visible wavelengths directly.Simple and compact visible lasers are booming with the development of blue laser diodes in recent years. In this Letter, we demonstrate the watt-level red laser with a single blue laser diode and Pr:YLiF_4 crystal. On this basis,the passively Q-switched pulse lasers are obtained with monolayer graphene and Co:ZnO thin film as the Q-switchers in the visible range.     

Study of passive Q-switching for flash-lamp-pumped 1.34-μm Nd:GdVO_4 laser

The static laser performance of a-growth Nd:GdVO4 crystal (a-cut, 4×4×25 (mm)) at 1.34μm pumped by flash-lamp is investigated with different transmissions of output couplers. With the output coupler transmission of T = 30%, the static output energy of 148 mJ is obtained when the pump energy is 35.2 J, and the corresponding electric-optical conversion efficiency is 0.42%. The Q-switched output of lasers with the output wavelength ranging from 1.3 to 1.6μm can be realized by using Co2 :LaMgAl11O19 (Co:LMA) as saturable absorber. A flash-lamp-pumped, passively Q-switched Nd:GdVO4 laser with Co:LMA as saturable absorber is demonstrated in plano-concave laser cavity. With the cavity length of 16.3 cm and pump energy of 19.8 J, the single-pulse output energy, pulse width, and peak power are obtained to be 4 mJ, 80 ns, and 5×104 W, respectively.     

Nd:GdVO4晶体的生长与光谱性能

采用Czochralski法生长了均匀透明的Nd:GdVO4晶体,测量了其室温偏振吸收谱,并与0.2mol·L^-1的NdCl3溶液的室温吸收谱进行了比较。根据Judd-Ofelt理论,拟合出晶体场唯象强度参数：Ω2=12.629×10^-20cm^2,Ω4=4.828×10^-20cm^2,Ω6=8.425×10^-20cm^2.计算了各能级的辐射跃迁几率AJ,J',振子强度PJ,J;,辐射寿命τ,荧光分支比βJ'等光学参量。并用LD激光器泵浦Nd:GVO4晶体,当量大泵浦功率为26W时,得到输出功率为14.3W波长为1.06μm的基频光,光-光转换效率为55%,斜效率为63%。     

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。     

Growth Defects in Cubic KTa1-xNbxO3 Crystal

Potassium tantalate niobate （KTa1-xNbxO3, KTN） crystals with different dimensions and quality situations were grown by Czochralski method. Crystal growth process and morphology properties of KTN are presented in this paper. It was found that some defects, such as bubble, inclusion, crack, dislocation etc., can all appear if the crystal is grown in an improper condition. The character and formation mechanism of such defects in macro growth are discussed. We consider that the CO2, which was not released absolutely during the sintering process and dissolved in the melt, led to bubbles. The composition of the inclusion caused by high pulling and rotation rates is KTN polycrystalline. The crack and dislocation in KTN crystal mainly come from improper temperature field. Etching and high-resolution X-ray diffraction （HRXRD） experiment results indicate that the central area is the defects concentrated.     

激光二极管抽运Er,Yb:Ca_4YO(BO_3)_3晶体实现1553nm激光输出

波长为1.55μm附近的激光,对人的眼睛是安全的,在光通讯上有重要应用。晶体中Er3 离子通过4I13/2→4I15/2跃迁可以产生该波长的激光。但Er3 对1.55μm波长激光有较强吸收,而对InGaAs和AlGaAs激光二极管(LD)的激光则吸收很弱,因此用LD抽运Er3 掺杂晶体输出1.55μm激光几乎是不可能的。但是若双掺Er3 ,Yb3 ,则可解决这个问题[1]。我们在研究Yb:Ca4YO(BO3)3(简称Yb:YCOB)晶体及其激光器[2]的基础上,制备了Er,Yb:YCOB晶体,测量了其光谱与激光特性,实现了1553nm激光输出。主要结果为:(1)以所合成的Ca4Er0.02Yb0.20Y0.78O(BO3)3…     

提拉法生长晶体的自等径控制

采用JPG技术有限公司所开发的自等径控制程序,利用上称重法实现了晶体生长的自等径控制(ADC).通过对生长曲线PID的具体分析及其他晶体生长相关参数的设置,以铌酸锂晶体为对象,成功实现了按预设程序进行的晶体生长自等径控制.     

电光晶体研究究进进展及其对称性性研研究

由电场引起的晶体折射率的变化称为晶体的电光效应,具有电光效应的晶体称为电光晶体。利用电光效应可以制作电光Q开关等重要光电器件。晶体的电光效应及其有效利用,均与其对称性密切相关。本文在综述电光晶体研究进展的基础上,推导了不同晶系中各晶类电光效应类型及其特点,并以电光Q开关的要求为例讨论了晶体的电光效应及其对称性之间的关系。从讨论结果得出:立方晶系Td-ˉ43m,三方晶系C3v-3m,四方晶系D2d-4ˉ2m,D4v-4mm和六方晶系D3h-6ˉm2,C6v-6mm点群中相应电光系数的横向或纵向效应可能有实用价值。在考虑旋光性影响后,立方晶系T-23,三方晶系D3-32,四方晶系中S4-4ˉ,六方晶系中C3h-6ˉ等也有可能应用。但是,电光晶体的应用与许多因素相关,对称性只是其中一个基本条件。