Passive Q-switching of Pulsed and CW Nd: YAG Lasers with Cr~(4 ): YAG

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Diode pumped Ho:YAG and Ho:LuAG lasers, Q-switching and?second harmonic generation

Direct diode pumped Ho:YAG generated laser pulses at 2.12???m with an optical to optical slope efficiency of 0.24. Ho:YAG and Ho:LuAG laser rods were evaluated with both wide and narrow bandwidth pump diodes. The laser wavelength varies with the level of pumping and optical design. This variation was found to be predictable. Second harmonic at 1.06???m was produced in a 6.0?mm long BBO crystal.     

Pre-pumped passively Q-switched Nd:YAG/Cr:YAG microchip laser

A pre-pumped passively Q-switched Nd:YAG/Cr: YAG microchip laser is demonstrated with a peak power of 7.5 kW at pulse repetition rate of serveral kilohertzs. The full-width at half-maximum (FWHM) is 734 ps, and the pulse energy is 5.5 μJ with a fundamental spatial mode. In this system, the pre-pumped microchip laser of Nd: YAG/Cr: YAG wafer which is bonded through the thermal-bonding technique has achieved a time jitter value of 12 μs and a Q-switched amplitude instability of 1.26% (1δ) through the pre-pumped modulation technique.     

基于Nd:YAG/Cr:YAG/YAG键合晶体LD侧面泵浦激光器

利用Nd∶YAG/Cr∶YAG/YAG键合晶体,建立了具有高平均输出功率的LD侧面泵浦被动调Q激光器系统.当Cr∶YAG的初始透过率为85%、最大泵浦光功率为187.5 W时,1 064nm激光的平均输出功率为83.68W.通过KTP晶体进行倍频,在最大泵浦光功率下,产生了27.2W532nm绿光激光脉冲,同时脉冲宽度和重复频率分别为210ns和21.2kHz;绿光单脉冲能量和峰值功率分别为1.28mJ和6.1kW;泵浦光(808nm)到倍频光(532nm)的光-光效率为14.5%.     

Diode-end-Pumped Nd:YAG Ceramic and Crystal Operation at 1,123 nm

We present a high-power diode-end-pumped continuous-wave Nd:YAG laser operating at 1,123 nm. Laser operation was carried out and compared using high optical quality Nd:YAG ceramics fabricated in-house and commercial Nd:YAG single crystals. At the absorbed diode pump powers of 23.2 and 28.0 W, output powers of 10.7 and 12.5 W at 1,123 nm were achieved for the employed ceramics and crystals as the laser material, which correspond to conversion efficiencies of 46.1% and 44.6%. For high-power lasers, the Nd:YAG ceramic has the advantage of a higher destructive threshold than that of commercial crystals.     

Nd:YAG倍频激光器

本器件的激光振荡器采用平凸非稳腔、透射式耦合双45°LiNbO_3电光调Q开关,输出为线偏振光,准球面波,经补偿后为平面波,通过二级放大器,最后用Ⅱ类相匹配的KDP倍频器将输出由1.06微米变为5300埃的绿光。本系统输出具有脉宽窄、束宽小、谐波功率大等特点。 本器件不仅用于精密激光人造卫星测距,也可作为高次谐波、非线性混频、染料激光器等的激励光源。 激光器电源分5路,分别供给激光振荡器及放大器的光泵闪光灯。闪光灯采用预电离方式工作。 主要技术指标:     

Yb:YAG及Cr,Yb:YAG晶体的发光特性

研究了室温下YbYAG的上转换荧光光谱,此荧光归因于Yb3+离子的"合作"发光和Yb3+离子到稀土杂质离子的能量转移.测试了YbYAG晶体的X射线荧光,发光峰对应于电荷迁移态到Yb3+离子的基态、激光态间的跃迁.研究了Cr,YbYAG晶体的荧光光谱,讨论了Cr4+激光输出的可能性.     

Nd:YAG激光棒

本所研制Nd:YAG激光棒已有十余年历史,所得成果能满足激光技术之要求。其规格、品质如下表所列:     

Cr:Tm:Ho:YAG (2.1 μm) and Nd:YAG (1.444 μm) pulsed-laser lithotripsy of bile duct stones

The Nd:YAG (1.444 m) and Cr:Tm:Ho:YAG (2.1 m) free-running laser systems of the output energy of 300 mJ per pulse and repetition rate 1 Hz have been developed and used for bile duct stones fragmentation study in vitro. A total of 67 human bile duct stones of known sizes, collected from surgical sources were used in the experiments. Insensitivity of the stones fragmentation to the type of the laser used, and insensitivity of the fragmentation efficiency to the type of stone, was observed. No pathological changes of the tissue were observed for non-human soft tissue laser irradiation (in vitro) by 1, 2, and 5 pulses of the Cr:Th:Ho:YAG radiation of the fluency of 1.6 J/cm². The lasers are found to be good candidates for laser lithotripsy.     

Passive Q-switching of 1.44 μm and 1.34 μm diode-pumped Nd:YAG lasers with a V:YAG saturable absorber

Spectroscopic data of a V³⁺:YAG passive Q-switch crystal were measured. The absorption recovery time was determined to be of 37±7 ns and the ground state absorption cross section was estimated to be 0.7×10^-18 cm² at 1.44 μm and 3.5×10^-18 cm² at 1.34 μm. Passively Q-switched operation of diode pumped 1.44 μm and 1.3 μm Nd:YAG lasers was demonstrated using this crystal as saturable absorber. Average output powers of 1.42 W (1.44 μm) and 1.56 W (1.34 μm) and pulse energies of 24 μJ (1.44 μm) and 25 μJ (1.34 μm) were observed, respectively. Received: 19 August 2002 / Published online: 12 February 2003 RID="*" ID="*"Corresponding author. Fax: +49-40/42838-6281, E-mail: kretschmann@physnet.uni-hamburg.de     

Nd:YAG/Cr~(4+):YAG/YAG键合晶体调Q激光输出特性研究

对激光二极管端面抽运Nd:YAG/Cr~(4+):YAG/YAG键合晶体的1 064nm被动调Q激光性能进行了研究.对比分析了Cr~(4+):YAG晶体初始透过率分别为84.9%和90.6%的调Q激光输出特性,以及不同耦合输出镜透过率对调Q性能的影响.结果表明,在特定抽运功率下,各输出特性参数的优化(高输出功率,高重复频率,窄脉冲宽度)分别对应一个最佳的输出镜透过率;随着抽运功率增加,对应最佳的输出镜透过率越大.对比两种初始透过率的Cr~(4+):YAG晶体对应的激光输出特性,84.9%初始透过率的晶体获得相对较低的平均输出功率,但相应的重复频率较小,脉冲宽度窄,使得调Q激光的峰值功率明显提高.采用30%透过率的耦合输出镜和10.4 W入射抽运功率下,获得了3.2 W平均输出功率、9.7ns脉冲宽度和52kHz重复频率的激光输出,经计算可知峰值功率达6.3kW.     

被动调QNd:YAG/Cr:YAG微晶片激光器的优化设计与实验

用数值求解速率方程的方法对被动调Q微晶片激光器进行了优化设计,并在实验中验证了这一优化效果。首先对速率方程进行数值求解,从数值求解的结果中得出了几个关键性参数,例如可饱和吸收体的初始透过率、输出镜反射率、激光器腔长、激光器腔内损耗、抽运激光光斑大小等,给出了关键性的参数对被动调QNd∶YAG/Cr∶YAG激光器的影响;然后基于数值求解的结果对微晶片激光器进行了优化设计,例如缩短激光腔长度,减小腔内损耗,选择合适的输出镜反射率、初始透过率和抽运激光光斑大小等;最后完成了两种不同参数的微晶片被动调QNd∶YAG/Cr∶YAG微晶片激光器的制作。     

高功率连续Nd:YAG激光器

本器件是一台高功率连续两棒串接的激光器。激光棒端面进行了修磨,以减少棒的热效应,提高激光的输出特性,并选取合适的泵浦功率和谐振腔结构,获得最佳的振荡模体积的匹配。 本器件可用于金属切割和焊接,医用激光中的肠瘤气化和切除等。 主要技术指标:     

二极管泵浦Nd:YAG激光器

CAMAS系统公司提供MLD7000——稳定锁模二极管泵浦固体Nd:YAG激光器系统。据说,以100MHz脉冲速率和20—500ps的脉冲宽度,可产生100mW的输出功率。在原系统的基础上,可获得Nd:YLF和较高重复率的改型系统。这种紧凑系统可完全得到控制,并能用电子学方法使其稳定。     

二极管泵浦Nd:YAG激光器

长期以来Nd:YAG激光器都是用闪光灯泵浦的。由于闪光灯的使用寿命有限,空间激光界的人们转而研制二极管泵浦激光器。最先泵浦用的激光二极管是GaAlAs双异质结激光二极管,它能在最佳泵浦波长808nm处连续工作。目前可用的激光二极管的泵浦效率可达20％或更高。根据速率方程,我们分析了Nd:YAG材料的能量转换过程。增益系数主要依赖于泵浦的通量密度和波长,而功率转换效率主要依赖于通过介质的1.06μm激光的通量密     

角抽运Yb:YAG激光器

报道了一种高功率准三能级激光器角抽运方法，抽运光从板条激光器结构中的板条工作介质的角注入，综合考虑抽运吸收、抽运亮度、晶体的掺杂浓度以及晶体尺寸等因素，进行了角抽运复合Yb:YAG激光器设计，实验上获得了最大连续输出功率400W, 斜效率28%的输出，实验结果充分证明了角抽运原理的正确性和应用于高功率激光器方面的可行性. 关键词： Yb:YAG 角抽运 复合晶体     

Light scattering and 2-μm laser performance of Tm:YAG ceramic

The scattering effect of Tm:YAG ceramic has been investigated and the scattering coefficient at 1064 nm wavelength is measured to be 0.014 cm⁻¹. Furthermore, a high power Tm:YAG ceramic laser with a slope efficiency of 10.7% has been built, which is end-pumped at a central wavelength of 805 nm. The 2-μm maximum output power is 7.1 W with an optical-optical conversion efficiency of 7.2%.     

Diode-pumped, Cr:YAG passively Q-switched and mode-locked Nd:YVO_4/KTP green laser

The phenomena of simultaneous Q-switching and mode-locking in a diode-pumped Nd:YVO4/Cr:YAG/ KTP green laser are reported and discussed in this paper. With 5.3-W pump power, by using a nearly hemispherical cavity (the cavity length is only 97 mm), the results of modulation depth of 70% and the period of 0.6 ns are obtained, the output power and the repetitive frequency of Q-switched pulse are 90 mW and 12 kHz, respectively.     

Passively Q-switched and mode-locked 1.3 μm Nd:YAG laser with Co:LMA saturable absorber

An xenon-lamp-pumped passively Q-switched and mode-locked (QML) Nd:YAG laser with Co:LMA saturable absorber at 1.3 μm is realized in a straight cavity. The modulation depth of mode locking pulse has reached 100%. The pulse energy and the pulse width of QML laser have been measured. The pulse width of the mode-locking laser is estamated to be 940 ps.     

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.