磷酸盐激光玻璃中水的测定

在Er~(3+)、Yb~(3+)和Nd~(3+)等离子激活的磷酸盐激光玻璃中,玻璃中的水对稀土离子亚稳态无辐射能量转移贡献很大。相对而言,基质的作用较小。对Nd~(3+)来说,~4F_(3/2)能级向~4I能级跃迁的无辐射过程主要受Nd~(3+)-OH基和Nd~(3+)-Nd~(3+)离子相互作用控制,而Nd~(3+)离子与OH基之间偶极子-偶极子相互作用参数大于Nd~(3+)离子间的作用。甚至对低掺杂浓度的激光玻璃,水的荧光猝灭作用也相当有效,因此,高量子效率的磷酸激光玻璃都必须是严格除水。近年来,人们对制造无水磷酸盐激光玻     

五磷酸钕单晶生长条件探索

五磷酸钕(简称NdPP)是一种高钕浓度(4×10~(21)厘米~(-3))的激光材料,比Nd:YAG(1.39×10~(20)厘米~(-3))约高30倍。其中Nd~(3+)不仅仅是作为激活离子掺入晶体中,而且本身又作为一个组分形成具有一定化学比的化合物(既是激活离子又是基质)。在NdPP中,钕离子间距较小(5.19埃),PO_4[即     

氙灯泵浦的NdP_5O_(14)晶体微型脉冲激光器已出光

西安五所用山东大学晶体研究室研制的大块NdP_5O_(14)晶体和该所研制的微型脉冲氙灯,设计组装了一台微型脉冲NdP_5O_(14)(Nd_xLa_(1～x)P_5O_(14))激光器,并于1979年1月8日输出激光。 NdP_5O_(14)——Ndpp是一种光学增益高的新型激光晶体。晶体中的Nd不是作为掺杂物进入基质,它本身就是化合物中的一个组分,就是说,它既是激活离子又是基质。Ndpp晶体中Nd~(3+)的浓度(4×10~(21)厘米~(-3))约为掺钕1％的YAG:Nd~(3+)中的Nd~(3+)浓度     

掺钕钆钪铝石榴石的生长、光学特性和连续激光作用

研究了由Gd_3Sc_2Al_3O_(12)(GADSCAG)组成的一致熔融稀土铝石榴石。对不掺杂材料沿<111>方向的理想晶体生长参数为转速20转/分,生长速率4.6毫米/小时。掺钕晶体的线性生长速率为2毫米/小时。测定了Nd:GADSCAG与激光作用有关的光学特性。室温下Nd~(3 )的1.06微米受激发射跃迁横截面为(3.2±0.3)×10~(-19)厘米~2,晶体中Nd~(3 )离子密度为1(原子)％时的荧光寿命为256±8微秒。最强泵浦带(0.81微米)的积分峰值吸收横截面为3.8×10~(-19)厘米~。对相同的Nd∶YAG和Nd∶GADSCAG棒的连续激光性能做了比较。     

Li-La磷酸盐激光玻璃Cr~(3+)→Nd~(3+)敏化

本文对Li-La磷酸盐玻璃单掺Cr~(3+)离子及双掺Cr~(3+)、Nd~(3+)离子的光谱性质进行了研究,测定了玻璃的吸收光谱、荧光光谱和荧光寿命。Li-La磷酸盐玻璃中Cr~(3+)→Nd~(3+)的能量转移效率为38％,最适当的钕离子浓度为2×10~(21)cm~(-3),Cr_2O_3含量≥0.1wt％。     

Nd_xLa_(1-x)P_5O_(14)中Nd~(3 )振荡强度和浓度猝灭

(Nd_xY_(1-x))_3Al_5O_(12)(YAG)和Nd_xLa_(1-x)P_5O_(14)(NdLaUP)的浓度猝灭特性是不同的。对YAG如其Nd~(3 )浓度为10~(21)原子/厘米~3,那么它的效率要比NdLaUP低得多。最近已研究出一种假设来解释NdUP和其它所谓“按化学当量计算”激光材料的浓度关系。对于NdUP中Nd-Nd间的平均距离约5埃来说,可以发生离子对之间的混杂互换。一个离子的5d结构与邻近离子的4f结构混合,产生类似与一个中心同位晶场交叠混合的附加跃迁几率。那么在高浓度时,寿命不是由于浓度猝灭减小,而是由于晶场交叠混合使跃迁几率浓度增强而减小。     

POCl_3-Z Cl_4-Nd(CF_3COO)_3和POCl_3-SnCl_4-Nd~(3 )激光液体的光谱参数

用光谱法求得POCl_3-ZrCl_4-Nd(CF_3COO)_3和POCl-SnCl_4-Nd~(3 )两种激光液体的Judd-Ofelt强度参数愿Ω_2、Ω_4、Ω_6分别为1.71、4.09、6.37和1.90、5.14、6.86(×10~(-20)厘米~2),从而计算了Nd~(3 )离子的~4F_(3/2)→~4I_J的辐射跃迁几率、荧光分支比、辐射寿命、辐射量子效率和~4F_3/2→~4I_(11/2)的诱导发射截面σ_p(分别为5.15×10~(-20)和5.69×10~(-20)厘米~2)。计算值与实验值符合较好。     

铍酸镧晶体中Nd~(3 )的光谱特性和激光性能

掺钕铍酸镧(La_2Be_2O_5:Nd~(3 )或BEL:Nd)激光晶体为单斜晶体,空间群为C_(2h)~6-C2/c。已测定光的主振动方向和相应的折射率与波长的关系。在1微米上,折射率n_x=1.9641,n_y=1.9974,n_z=2.0348。Nd~(3 )能级在最下的五条多重谱线上。在此晶体中钕的低浓度荧光寿命极限为150微秒,观察到两种激光跃迁的受激发射截面在E‖X时为2.1×10~(-19)厘米~2而当E‖Y时则为1.5×10~(-19)厘米~2。激光波长分别为1.070和1.079微米。在测试中发现La_2Be_2O_5:Nd的斜率效率比Y_3Al_5O_(12):Nd(YAG:Nd)的斜率效     

脉冲泵浦Nd~(3 ):Gd_3Ga_5O_(12) 1.054微米激光

曾有人研究过掺钕Gd_3Ga_5O_(12)(GGG)激光器的振荡效率、阈值和增益,并将之与Nd~(3 )∶YAG激光器作过比较。资料〔1〕首先报导了闪光灯泵浦Nd~(3 )∶GGG晶体1.062微米的激光发射。最近,研究将Nd~(3 )∶GGG激光器用于ED-2激光玻璃高功率激光系统,来代替Nd~(3 )∶YAG激光器锁模主振荡器。Nd~(3 )∶GGG具有1.054微米激光作用的可能性。本文首先实验证明闪光灯泵浦1.054微米Nd~(3 )∶GGG的激光作用。此波长与有希望用于高功率     

Nd~(3+)在LaMgAl_(11)O_(19)晶体中的光谱特性

一、前言 已获得广泛应用的铝酸盐激光晶体,如YAG:Nd~(3+)、YAP:Nd~(3+)有许多优点,但它们的Nd~(3+)离子发光浓度粹灭效应严重,限制了掺杂浓度。YAG:Nd~(3+)只能掺入约2×10~(20)/cm~3。为了探索高Nd~3+)浓度的激光晶体,法国科学家在1981年制备了LaNdMgAl_(11)O_(19)晶体。我们用提拉法生长了LNA单晶,测量了77K和300K的吸收谱、荧光及偏振荧光谱和荧光寿命,并获得了57mJ的1.054/,m的脉冲激光输出。     

制备Nd3+:Gd3 Ga5O12透明陶瓷的纳米粉体

由于激光晶体的生长周期长、成本高等缺点,激励人们不断地探索新的激光材料。透明陶瓷就是最近发展起来的一种。采用溶胶-凝胶法合成了用于制备掺钕的钆镓石榴石(Nd3 ∶Gd3Ga5O12)透明激光陶瓷的多晶纳米粉体。采用X射线衍射(XRD)和扫描电子显微镜(SEM)对样品的晶相和形状进行了分析。结果表明,温度为1000℃,灼烧12 h,获得单分散、形状规则、似球形的Gd3Ga5O12(GGG)纳米粉体,且随着烧结温度的提高前驱粉体粒度不断增加。荧光发射的最强峰位于1062.7 nm处,对应于Nd3 的4F3/2→4I11/2能级跃迁。     

End-pumped Nd:LaF3 and Nd:LaMgAl11O19 lasers

Nd:LaF₃ and Nd:LaMgAl₁₁O₁₉ (LMA) are promising candidates for pulsed diode-laser-pumped lasers because they have relatively long upper state lifetimes and large absorption bandwidths compared to other Nd³⁺ doped materials. Crystal growth of LMA and the spectroscopic properties of both materials are described. Continuous-wave (CW) end-pumped lasers have been demonstrated in these materials using a Ti:Al₂O₃ laser to simulate the diode-laser pump source. Slope efficiencies of 47% for Nd:LaF₃ and 32% for Nd:LMA were obtained. The results for Nd:LaF₃ are typical for end-pumped, CW, Nd³⁺ lasers; the lower slope efficiency for Nd:LMA is attributed to excited-state absorption     

Spectroscopic and stimulated emission Characteristics of Nd/sup 3+/ in transparent YAG ceramics

Nd: YAG ceramic materials have been synthesized using vacuum sintering technique with the raw materials prepared by the nano-crystalline methods. The spectroscopic studies suggest overall improvement in absorption and emission and reduction in scattering loss. Judd-Ofelt analysis has been employed to compute the relevant spectroscopic and radiative parameters of the material. The SEM and TEM measurements reveal the excellent optical quality of the ceramic with low pore volume and narrow grain boundary. Fluorescence and Raman measurements reveal that the Nd/sup 3+/-doped YAG ceramic is almost equivalent to its single-crystal counterpart in its radiative and nonradiative properties. Individual Stark levels for /sup 2s+1/L/sub J/ manifolds are obtained from the absorption and fluorescence spectra and are analyzed to identify the stimulated emission channels possible in the Nd: YAG ceramic. Laser performance studies favor the use of high-concentration Nd: YAG ceramics in the design of an efficient microchip laser. With 4 at% Nd: YAG ceramic acting as a microchip laser, we obtained a slope efficiency of 40%. High-power laser experiments yield an optical-to-optical conversion efficiency of 30% for Nd (0.6 at%):YAG ceramic as compared to 34% for an Nd (0.6 at%):YAG single crystal. The oscillation experiments at 1.3 mm gives a slope efficiency of 35%. Optical gain measurements conducted in these materials also show values comparable to single crystal, supporting that these materials could be suitable substitutes to single crystals in solid-state laser applications.     

Nd:(La,Sr)(Al,Ta)O3晶体的生长及光谱性能的研究

应用中频感应提拉法生长了新型的Nd：（La，Sr）（Al，Ta）O3（Nd^3＋：LSAT）晶体。运用电感耦合等离子体原子发射光谱仪（ICPAES）测定Nd^3＋离子在Nd^3＋：LSAT晶体中的分凝系数为0．587。X射线粉末衍射（XRPD）测试结果表明Nd^3＋：LSAT晶体与LSAT晶体同构。研究了不同退火条件对晶体光谱性能的影响。分析了Nd^3＋：LSAT晶体的光谱性能，Nd^3＋：LSAT晶体的荧光寿命为290μs。比较了Nd^3＋：LSAT和Nd^3＋：YAG，Nd^3＋：YVO3等晶体的光谱参数。结果表明Nd^3＋：LSAT是一种适合激光二极管（LD）抽运的、有前景的激光增益介质。     

Lutetium effects on the UV absorption spectra of Nd:YAG

Spectroscopic observations were made on Lu:Nd:YAG and Nd:YAG laser materials. Variations in the UV absorption strengths are described and related to the presence of Lu³⁺. These results indicate that an optimum Lu/Nd ion ratio exists that will yield minimum absorption by the host over the wavelength range0.4-0.24 mum. The reduction in absorption will minimize nonuniform heating effects that should lead to better laser performance under certain conditions.     

Characterization and control of gamma and proton radiation effectson the performance of Nd:YAG and Nd:YLF lasers

The laser performance of Nd:YAG and Nd:YLF crystals longitudinally pumped at 800 mm was evaluated before and after exposure to ⁶⁰Co gamma rays and high energy (30-50 MeV) protons. Both forms of radiation created the same damage centers in the respective crystals, which reduced optimal output primarily by absorbing the laser emission. While the radiation induced loss at the lasing wavelength for high quality Nd:YAG reached a limiting value of ~0.015 cm^-1 at 100 krad exposure levels, the loss in Nd:YLF was significantly larger than in Nd:YAG for all comparable dosage levels, and did not appear to have a limiting value. Given the relatively short path lengths of the laser crystals that were tested, the loss could be overcome for both materials under pulse-pumped operation, demonstrating that certain Nd lasers can be effectively radiation hard by design. Additionally, for the first time, Cr³⁺ was codoped with Nd in YAG (with minimal Cr⁴⁺ formation) yielding a high performance material with a significantly reduced radiation susceptibility     

共掺Ce对Nd,Eu:ZnWO4激光晶体的敏化作用

为了研究共掺Ce对Nd,Eu∶ZnWO4激光晶体的敏化作用,采用提拉法生长了无宏观缺陷的一系列Nd∶ZnWO4,Ce∶ZnWO4,Eu∶ZnWO4,Ce∶Nd∶ZnWO4和Ce∶Eu∶ZnWO4晶体,并进行了X射线衍射(XRD)、吸收光谱和荧光光谱的测试.测试结果表明,在ZnWO4晶体中Ce3 离子在324 nm附近有很强的吸收,可以有效地吸收抽运能量;Ce3 离子与Nd3 离子和Eu3 离子间存在明显的能量转移,使Nd3 离子在474 nm,572 nm的上转换荧光以及Eu3 离子在613 nm处的荧光强度明显增强,并提出了敏化机制和能量转移过程.结果说明,共掺Ce对Nd,Eu∶ZnWO4激光晶体有较好的敏化作用,有助于提高激光晶体的发光强度.     

含能材料激光点火性能的试验研究

分析了固体含能材料光吸收性的特点,采用了既利于材料吸收又便于普通光纤传输的大功率固体Nd~(3+):YAG激光器,对各种含能材料进行了激光点火性能的试验研究,成功测得了各种含能材料的点火过程曲线,并对影响含能材料激光点火性能的各种因素(激光能量、脉冲持续时间、不同药粒等)进行了实验分析。结果表明,不同含能材料的激光点火性能存在较大的差异,这不仅与激光特性有关,而且与含能材料的热物性有着密切的关系。这必将为含能材料激光点火系统的设计提供参考和依据。     

复合单晶被动调Q光纤激光器的制备与数值模拟

为了开发新型激光材料,采用激光加热基座法将Cr4 ∶YAG单晶光纤和Nd3 ∶YAG单晶光纤生长为一体化复合单晶光纤。利用速率方程理论,得到包含激光增益介质反转密度、光子密度和饱和吸收介质基态布居数密度的速率方程组。通过数值计算,求得复合单晶Cr4 被动调Q光纤激光器的若干重要特征参量及其与抽运率的函数关系曲线,计算结果较好地符合了实验结果,从而可以为优化设计这类单晶光纤激光器提供指导。     

钾蒸气中双光子共振四波混合的差频效应

在钾蒸气中观察到了双光子共振四波混合的差频效应。YAG:Nd~(3+)激光器的红外光波(ω_3)和 YAG:Nd~(3+)激光的二次谐波泵浦的可调谐染料激光器的可见光波(ω_1)用作入射波。当染料激光的两个光子的能量等于钾原子高激发态13s 和基态4s 间的能量差时,产生了一个新的波长为4052的相干光波(ω_4=2ω_1-ω_3)。