Nd:GGG晶体生长、光谱性能及激光性能

采用提拉法生长掺钕钆镓石榴石(neodymium-doped gadolinium gallium garnet, Nd: GGG)激光晶体,选择最佳工艺参数:提拉速率为2～4mm/h:转速为20～40r/min;冷却速率为20℃/h.测试了晶体的吸收和荧光光谱,结果表明:主吸收峰位于808nm,主发射峰位于9430cm-1,对应于Nd3 的4F3/1-4I11/2跃迁.对晶体样品进行了激光性能测试.结果表明:当泵浦功率为900mW时,对泵浦光的吸收效率为85%,激光输出波长约为1μm,激光输出功率为305mW,激光阈值功率为380mW,光-光转换效率达57.8%,斜效率达57.6%.     

Nd:YAG透明陶瓷的制备及激光输出

用溶胶-凝胶法制备了Nd3+掺杂摩尔分数为2.7%的Nd:AG粉体。采用真空热压和热等静压相结合工艺制备了Nd:YAG透明陶瓷。测试了样品的显微结构、透过光谱、吸收光谱、荧光光谱和激光性能。结果表明:样品的晶粒尺寸为2～10μm,晶界处存在少量气孔;1.7mm厚样品1064nm波长的透过率为78%;样品808nm处吸收峰对应的吸收系数为27.5cm-1;808nm泵浦的主荧光峰位于1064nm,荧光寿命为135μs;LD端面泵浦尺寸3mm×3mm×1.5mm的样品获得了最大输出功率170mW的激光输出,光-光转换效率为8%,斜效率为13.8%。     

Nd：GGG晶体生长、光谱性能及激光性能（英文）

采用提拉法生长掺钕钆镓石榴石（neodymium-doped gadolinium gallium garnet,Nd：GGG）激光晶体,选择最佳工艺参数：提拉速率为2～4mm/h;转速为20～40r/min;冷却速率为20℃/h。测试了晶体的吸收和荧光光谱,结果表明：主吸收峰位于808nm,主发射峰位于9430cm^–1,对应于Nd3＋的4F3/2–4I11/2跃迁。对晶体样品进行了激光性能测试。结果表明：当泵浦功率为900mW时,对泵浦光的吸收效率为85%,激光输出波长约为1μm,激光输出功率为305mW,激光阈值功率为380mW,光–光转换效率达57.8%,斜效率达57.6%。     

低阈值激光自倍频晶体Nd:GdCa4O(BO3)3

利用提拉法生长出大尺寸、高质量的激光自倍频晶体Nd:GdCa4O(BO3)3 (Nd:GdCOB).测量了Nd:GdCOB晶体的室温偏振透过谱及荧光谱,计算了其在530 nm和811 nm处沿不同主轴的吸收截面.利用电光调Q-Nd:YAG激光器,首次测试得出晶体位于XY主平面外的(θ=66.8°,φ=132.6°)位相匹配方向的有效倍频系数为2.1 pm/V;而在XY主平面内(θ=90°,φ=46°)的方向为0.7 pm/V.通过计算和实验比较,认为前者位相匹配方向为最佳倍频方向.用钛宝石连续激光器对这两个方向的样品进行自倍频实验,在520 mW的输入功率时获得绿光输出为11.3 mW,光-光转换效率为2.3%,激光阈值低于1 mW.目前θ=66.8°,φ=132.6°匹配方向在大功率钛宝石泵浦下,转换效率可以达到14.4%.     

Nd∶YLiF4晶体的声光调Q脉冲激光特性研究

在激光二极管端面泵浦的情况下,采用耦合透过率为10％的输出镜,研究了Nd∶YLiF4晶体的声光调Q脉冲激光特性.当重复频率为1O kHz,泵浦功率为5.94 W时,获得了540 mW的最大平均输出功率,光光转换效率和斜效率分别为9.09％和10.7％.当重复频率为1 kHz时,获得了最佳的脉冲实验结果:最高峰值功率为49.2 kW,最大单脉冲能量为295μJ,最小脉宽为6 ns.     

固相反应法制备高浓度掺杂Nd:YAG激光透明陶瓷及其性能

用固相反应和真空烧结技术,成功制备了高质量的4.0%(摩尔分数)Nd:YAG透明陶瓷,并对样品的显微结构、光学透过率、光谱性能和激光性能进行了表征.结果表明:样品的平均晶粒尺寸约为10 μm;样品(厚度为2.8 mm)在1 064 nm处的透过率高达79.5%;主吸收峰位于807 nm处,峰值吸收系数为13.9 cm-1,激光波长1 064 nm处的吸收系数为0.2 cm-1;主荧光发射峰位于1 064 nm处,荧光寿命为102 μs.用激光二极管(808 nm)端面泵浦Nd:YAG陶瓷样品(泵浦源最大输出功率为1 000 mW),获得了波长为1 064 nm的连续激光输出,输出功率17 mW(最大泵浦吸收功率为998 mW),斜率效率为6.1%,激光阈值约733 mW.     

掺钕钆镓石榴石晶体的激光性能

采用提拉法生长了Nd：Gd3Ga3O12（Nd：GGG）晶体。切割后的样品经过端面抛光,测试了荧光光谱、吸收光谱和激光性能。荧光光谱表明：晶体的最强的荧光发射峰位于1062nm,是Nd^3＋的4^F3/2-4^I11/2谱项导致的荧光发射。由吸收光谱发现：Nd：GGG晶体的最强吸收峰位于808nm,表明该晶体适合于激光二极管泵浦．并且吸收峰强度随掺杂离子浓度的增加而增加。激光性能测试结果表明：激光二极管泵浦时光-光转换效率为33.＋8％,斜效率为57.8％。     

钛宝石激光器泵浦(Cr4+,Nd3+):YAG晶体的自调Q激光器

用钛宝石激光器泵浦单块(Cr4+, Nd3+:YAG)晶体获得了1.064 μm的自调 Q激光输出.激光输出的模式是稳定的单纵模, 泵浦的阈值功率为63 mW, 脉冲宽度(F WHM)为8 ns, 斜率效率高达24%.随着泵浦功率的变化, 脉冲宽度保持不变, 而重复频率则在变化.这种把激光增益介质和可饱和吸收体结合到一起的自调Q激光晶体的研究将有利于固体激光器的全固化、集成化和实用化.     

Yb∶NaY(WO_4)_2激光晶体的光谱性能

采用提拉法生长出了Yb∶NaY(WO4 ) 2 晶体 ,给出了晶体生长的最佳工艺参数 :拉速 0 .5～ 4mm/h ,转速 3 0～ 40r/min ,冷却速率 18℃ /h。由TGDTA分析得到晶体的熔点为 12 0 9℃。测试了该晶体的Raman光谱、吸收光谱和荧光光谱 ,计算了吸收光谱和荧光光谱中的有关参数。结果表明 :该晶体发射波长为 10 10nm ,在 848,968nm附近有较强、较宽的吸收峰 ,适合于LD泵浦     

钛宝石激光器泵浦(Cr~(4 ),Nd~(3 ))∶YAG晶体的自调Q激光器

用钛宝石激光器泵浦单块 (Cr4 ,Nd3 ∶YAG)晶体获得了1.0 6 4μm的自调Q激光输出 .激光输出的模式是稳定的单纵模 ,泵浦的阈值功率为 6 3mW ,脉冲宽度 (FWHM)为 8ns,斜率效率高达2 4% .随着泵浦功率的变化 ,脉冲宽度保持不变 ,而重复频率则在变化 .这种把激光增益介质和可饱和吸收体结合到一起的自调Q激光晶体的研究将有利于固体激光器的全固化、集成化和实用化 .     

Solid-state-reaction fabrication and properties of a high-doping Nd:YAG transparent laser ceramic

High-quality neodymium-doped yttrium aluminum garnet (Nd:YAG) transparent ceramic (4.0 mole percent) was fabricated by a solid-state reaction method and vacuum sintering. The microstructure, optical transmittance, spectral properties and laser performance were investigated. The average grain size of the sample is about 10 ?m. The transmittance of a 2.8-mm thick sample reaches 79.5% at the laser wavelength of 1064 nm. The highest absorption peak is centered at 807 nm and the absorption coefficient is 13.9 cm^-1. The absorption coefficient at the laser wavelength is 0.2 cm^-1. The main emission peak is at 1064 nm and the fluorescence lifetime is 102 ?s. A laser diode (808 nm) whose maximum output is about 1000 mW was used as a pump source and an end-pumped laser experiment was performed. The 1064 nm-CW-laser output was obtained and the threshold is 733 mW. With 998 mW of maximum absorbed pump power, a laser output of 17 mW is obtained with a slope efficiency of 6.1%.     

Solid-state-reaction fabrication and properties of a high-doping Nd:YAG transparent laser ceramic

High-quality neodymium-doped yttrium aluminum garnet (Nd:YAG) transparent ceramic (4.0 mole percent) was fabricated by a solid-state reaction method and vacuum sintering. The microstructure, optical transmittance, spectral properties and laser performance were investigated. The average grain size of the sample is about 10 mm. The transmittance of a 2.8-mm thick sample reaches 79.5% at the laser wavelength of 1064 nm. The highest absorption peak is centered at 807 nm and the absorption coefficient is 13.9 cm⁻¹. The absorption coefficient at the laser wavelength is 0.2 cm⁻¹. The main emission peak is at 1064 nm and the fluorescence lifetime is 102 μs. A laser diode (808 nm) whose maximum output is about 1000 mW was used as a pump source and an endpumped laser experiment was performed. The 1064 nm-CW-laser output was obtained and the threshold is 733 mW. With 998 mW of maximum absorbed pump power, a laser output of 17 mW is obtained with a slope efficiency of 6.1%. __________ Translated from Journal of The Chinese Ceramic Society, 2007, 35(12): 1600–1604 [译自: 硅酸盐学报]     

激光透明陶瓷研究的历史与最新进展

由于透明陶瓷具有许多比单晶优越的性能,因此透明多晶陶瓷激光器成为近年来二极管泵浦固态激光器领域的研究焦点.目前,在Nd:YAG陶瓷激光器中,已获得高于1 kw的高激光输出功率和高于65%的斜率效率,在Yb掺杂的倍半氧化物陶瓷激光器中,实现了二极管泵浦的超快飞秒锁模激光输出以及82.4%的所有陶瓷激光器中最高的斜率效率.报道了中国近来在Nd:YAG和Yb/Nd掺杂的氧化镧钇透明陶瓷方面的研究进展,由中国科学院上海硅酸盐研究所制备的Nd:YAG陶瓷激光器最大激光输出斜率效率为23.2%,由上海大学制备的一种新的Yb:Y1.8La0.2O3陶瓷激光器最大激光输出斜率效率达到52%.     

掺Nd系LiNbO3晶体的生长及外泵浦位相共轭激光器的特性

用提拉法生长Nd:LiNbO3(Nd:LN),In:Nd:LN和Ce:Nd:LN晶体.测试晶体的紫外-可见吸收光谱和抗光损伤能力.结果表明:Nd:LN晶体的吸收边相对同成分纯LN晶体向长波方向移动;In:Nd:LN晶体的吸收边相对Nd:LN晶体向短波方向移动;Ce:Nd:LN晶体的吸收边向长波方向移动.In:Nd:LN晶体的抗光损伤能力比Nd:LN晶体的提高1个数量级以上.以掺Nd系LN光折变晶体为位相共轭镜,He-Ne气体为激活介质,构成外泵浦位相共轭激光器.实验表明:掺Nd系LN晶体外泵浦位相共轭激光器的输出特性稳定,In:Nd:LN晶体的输出光强比Fe:LN晶体的提高了近1个数量级.     

Diode-Pumped Passively Q-Switched Nd:YAG Ceramic Laser with a Cr4+:YAG Crystal-Satiable Absorber

Transparent polycrystalline Nd:YAG ceramics were fabricated by solid-state reactive sintering a mixture of commercial Al₂O₃,Y₂O₃, and Nd₂O₃ powders. The powders were mixed in ethanol and doped with 0.5 wt% tetraethoxysilane, dried, and pressed. Pressed samples were sintered at 1750°C in vacuum. Transparent fully dense samples with average grain sizes of 10 μm were obtained. The 1 at.% Nd:YAG ceramic was used to research passively Q-switched laser output with a Cr⁴⁺:YAG crystal as a saturable absorber. An average output power of 94 mW with a pulse width of 50 ns was obtained when the incident pump power was 750 mW. The slope efficiency was 13%. The pulse energy is 5 μJ, and the peak power is about 100 W.     

Laminar-Structured YAG/Nd:YAG/YAG Transparent Ceramics for Solid-State Lasers

A laminar-structured YAG/1.0 at.% Nd:YAG/YAG transparent ceramic was fabricated by a solid-state reaction method and vacuum sintering using high-purity α-Al₂O₃, Y₂O₃, and Nd₂O₃ as raw materials with tetraethoxysilane as a sintering aid. The microstructure, the optical property, and the laser performance of the ceramic composite prepared were investigated in this paper. It is found that the sample exhibits a pore-free structure and the average grain size is about 15 μm. There is no secondary phase both at the grain boundary and at the grain matrix. The optical transmittance of the sample (5.0 mm thick) is 80.2% at 1064 nm. The lasing sample is Φ16.2 mm × 5.0 mm in size, mirror polished on both sides and without a coating. A laser diode (808 nm) was used as a pump source with a maximum output of about 1000 mW, and the end-pumped laser experiment was demonstrated. With 658 mW of maximum absorbed pump power, a laser output of 8 mW has been obtained with a slope efficiency of 4.0%.     

2种不同激光对钛宝石辐照作用的研究

分别采用波长为193 nm的ArF准分子激光与波长为800 nm、脉冲宽度为120 fs的飞秒激光对温梯法生长的钛宝石进行辐照,并对辐照前后的吸收谱、荧光谱及电子顺磁共振(EPR)谱进行了检测。2种不同辐照的结果表明:218 nm及266 nm吸收峰并不是完全由同一种色心所引起的。通过对比不同品质因数(FOM)值的钛宝石样品在420 nm处的荧光谱,发现准分子激光辐照后420 nm处荧光强度降低,表明样品中Ti~(4 )离子浓度降低。而在飞秒激光辐照下荧光强度增大,即Ti~(4 )浓度增大。根据2种激光的波长,功率密度及辐照方式的差异对于2种辐照产生不同结果做出了解释。     

掺钕钨酸钆钠晶体生长、结构及光谱特性

采用提拉法生长了尺寸为φ(30～35)mm×80mm的掺钕钨酸钆钠[Nd:NaGd(WO4)2,Nd:NGW]晶体。生长Nd:NGW晶体的最佳工艺参数为:晶体的提拉速率为1～2mm/h,晶体转速为15～18r/min,冷却速率为10℃/h,液面上轴向温度梯度为0.7～1℃/mm。通过热重-差热分析(thermogravimetry-differential thermal analysis,TG-DTA),X射线衍射(X-ray diffraction,XRD)对晶体进行表征。测试了晶体的红外及Raman光谱,分析了晶体的振动模式,并将晶体振动光谱进行归属。由TG-DTA曲线得到晶体熔点为1251.7℃。XRD分析表明:晶体属于四方晶系、白钨矿结构、I41/a空间群,晶胞参数a=0.53213nm,c=1.13070nm。吸收光谱表明:Nd:NGW晶体在805nm附近有较强、较宽的吸收峰,吸收截面积为3.581×10-20cm2,适合于激光二极管泵浦。     

Fabrication,microstructure, and optical properties of Tm:Y3ScAl4O12 laser ceramics

Transparent 4 at.% Tm:Y₃ScAl₄O₁₂ (Tm:YSAG) laser ceramics were fabricated by solid-state reaction combined with vacuum sintering method. The 4 at.% Tm:YSAG ceramic sample sintered at 1800°C for 30 hours possesses homogenous microstructure and excellent optical properties, showing a transmittance of 79.3% at 2000 nm. The absorption and emission spectra of the Tm:YSAG ceramics are studied and compared with those of 4 at.% Tm:Y₃Al₅O₁₂ ceramics. The introduction of Sc³⁺ greatly affects the energy levels of the Tm³⁺, causing the disappearance and degeneration of some absorption and emission peaks in the middle infrared region. The laser performance of the 4 at.% Tm:YSAG ceramics is also tested in the Quasi-continuous-wave (QCW) mode by pumping with a 790 nm laser diode (LD). A maximum laser output power of 0.54 W with a slope efficiency of 4.8% is achieved, which is the first laser output for Tm:YSAG ceramics.