High-power Nd:YAG planar waveguide laser with YAG and Al2O3 claddings

Thermal effects in Nd:YAG planar waveguide lasers with non-symmetrical claddings are discussed. The heat generated in the active core can be removed more efficiently by directly contacting the active core to the heat sink. Several cladding materials are compared to optimize the heat removal. Furthermore, uniform pumping is achieved with oblique edge-pumping technique. Using quasi-CW pumping at 1 KHz repetition rate, an average output power of 280 W with a slope efficiency of 38% is obtained with a positive unstable resonator. (C) 2008 Elsevier B.V. All rights reserved.

Passively Q-switched Nd:YVO4 laser with a Cr4+:YAG crystal saturable absorber

We demonstrate, for the first time as far as Re known, a passively Q-switched operation of a Nd:YVO4 laser in which a Cr4+:YAG crystal and a laser-diode bar are used as the saturable absorber and the pump source, respectively. Stable laser pulses as short as 28 ns with 20-mu J energy can be generated with this laser, which has the advantages of simplicity, high efficiency, and good long-term stability. (C) 1997 Optical Society of America.

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 degrees C in vacuum. Transparent fully dense samples with average grain sizes of 10 mu m 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 mu J, and the peak power is about 100 W.

钕玻璃、Nd：YAG和Nd：GGG热容激光特性比较

考虑固体热容激光器对工作介质的要求，对比分析了掺钕的玻璃、YAG和GGG的多种材料性能。并对三者在激光工作周期内的瞬态温度场及热应力进行了数值模拟。结果表明：在给定的边界及工作条件下，当钕玻璃激光器以热容方式工作，时间为5S时，介质最高升温超过400K，最大热致应力为25MPa，接近其断裂极限的50％。在此条件下进行冷却，当水温为283K时，需经过约120S才基本恢复到初始工作状态。而Nd：YAG和Nd：GGG两种介质在相同输入工作条件下，工作时间可达10S，且温度分布相对平坦，温差和热应力较小，经水冷约

LD 侧面抽运Nd :YAG陶瓷激光器运转条件下归一化热参数优化理论及实验研究

The suppressing effect of laser extraction on the non-radiation transition process is taken into account when the heat model of gain media is developed. Based on the developed heat model, the heat generation in the operating LD side-pumped Nd: YAG ceramic lasers is quantified through using the normalized heating parameter, which can be deduced from the experimental results of the slope efficiency and the absorbed pumping power of the gain media. The main factors which influence on the heat generation are investigated by studying the normalized heating parameter, and the results show that the changes of the laser extraction efficiency, the beam overlap efficiency and the Nd3+ concentration will result in obvious variations of the normalized heating parameter. In this work, the laser extraction efficiency increases to 0.905 by the optimization of the transmission of the output coupling, and the normalized heating parameter decrease to 0.474, correspondingly.

钛宝石激光器端面抽运Nd：YAG陶瓷激光器热沉积理论和实验研究

通过热沉积系数研究在激光提取条件下掺杂原子分数为1.0%的Nd：YAG陶瓷激光器中热沉积问题.热沉积系数定义为热沉积功率与激光器输出功率之比.在理论分析基础上,通过测量激光器斜率效率来间接测定热沉积系数,实验测定的热沉积系数值为0.63.建立激光提取条件下Nd：YAG陶瓷发热模型,讨论了影响热沉积系数的主要因素.结果表明：热沉积系数对Nd：YAG陶瓷的辐射量子效率、交叠效率以及激光提取效率的变化非常敏感.为有效减少介质内热沉积,在激光器优化设计中交叠效率和激光提取效率是需要着重考虑的参数.所得结果可为进一

位相锁定来自同一侧面抽运Nd：YAG板条的两束激光

实验研究了腔内位相锁定来至一LAD侧面抽运的Nd：YAG板条的两束激光，输出镜面出现干涉条纹，获得1.13W的相干光，其组束效率达到64.9%，相干度约60%。实验中发现只需要一根作为滤波的金属丝放在离输出镜合适的位置都就能有效稳定干涉条纹，金属丝引起的损耗低于8%。

边缘泵浦被动调Q的Nd：YAG薄片激光器

文中报道了一台采用激光二极管部分边缘泵浦方式的高功率薄片激光器，晶体尺寸是1 mm×10 mm×60 mm。Cr4+：YAG被用来作为被动调Q晶体，在重复频率高于10kHz时，获得了脉宽10ns，平均功率70W，斜线效率为36\%的激光输出。通过控制泵浦光束直径的大小，我们在厚度方向得到了近似衍射极限的光束输出。整个激光器结构紧凑，大小为60 mm×174 mm×150 mm。

Passively Q-switched Yb : YAG laser with Cr4+: YAG as the saturable absorber

By using a continuous-wave Ti:sapphire laser as a pumping source, we demonstrated a passively Q-switched Yb:YAG laser at room temperature with Cr4+:YAG as the saturable absorber. We achieved an average output power of as much as 55 mW at 1.03 mum with a pulse width (FWHM) as short as 350 ns. The initial transmission of the Cr4+:YAG has an effect on the pulse duration (FWHM) and the repetition rate of the Yb:YAG passively Q-switched laser. The Yb:YAG crystal can be a most promising passively Q-switched laser crystal for compact, efficient, solid-state lasers. (C) 2001 Optical Society of America.

Temperature dependence of the 1.064-mu m stimulated emission cross-section of Cr : Nd : YAG crystal

The fluorescence emission spectra of Cr:Nd:YAG crystal are measured and the effective stimulated emission cross-section of the crystal is obtained from -80 to +80 degrees C. A linear temperature dependence between -80 and +80 degrees C is reported for the 1.064-mu m peak stimulated emission cross-section of Cr:Nd:YAG crystal. (C) 2005 Elsevier Ltd. All rights reserved.

温度梯度法生长Nd：YAG晶体的1200W激光输出

用温度梯度法（TGT）生长了大尺寸的Nd：YAG激光晶体，测试了室温下的吸收谱并利用吸收谱研究了Nd离子在YAG晶体中的分布。比较了温度梯度法与提拉法生长晶体的区别。根据热容激光的原理，利用生长的Nd：YAG激光晶体片设计了热容激光器，利用侧面抽运，获得了1200w的激光输出，工作时间为2s，光-光转换效率为30％。

Experimental investigation of intracavity absorber low temperature GaAs in diode-pumped Nd : GdVO4 laser

A passively Q-switched and mode-locked diode-pumped Nd:GdVO4 laser was demonstrated using a low-temperature-grown GaAs wafer (LT-GaAs) as an intracavity saturable absorber. The maximal Q-switched mode-locked average output power was 750 mW with the Q-switched envelop having a repetition rate of 167 kHz. The mode-locked pulse trains inside the Q-switched pulse envelope had a repetition rate of similar to 790 MHz.

Q-switched and mode-locked diode-pumped Nd : GdVO4 laser with low temperature GaAs saturable absorber

Low temperature GaAs (LT-GaAs) was successfully grown at the temperature of 550 degrees C by metal organic vapor phase epitaxy on a semi-insular GaAs substrate. With such an absorber as well as an output coupler we obtain Q-switched mode-locked (QML) 1064 nm Nd:GdVO4 laser pumped by diode laser with high repetition rate, formed with a simple flat-flat cavity. The repetition rate of the Q-switched envelope increased from 100 to 660 kHz as the pump power increased from 2.28 to 7.29 W. The mode-locked pulses inside the Q-switched pulse envelope had a repetition rate of similar to 1.36 GHz. A maximum average output power of 953 mW was obtained. The dependence of the operational parameters on the pump power was also investigated experimentally. (C) 2005 Elsevier B.V. All rights reserved.

Passively Q-switched and mode-locked diode-pumped Nd : YVO4 laser with LT-GaAs output coupler

We have demonstrated an efficient and compact passively Q-switched and mode-locked (QML) 1064 nm Nd:YVO4 laser by using a low temperature grown GaAs (LT-GaAs) saturable absorber as well as an output coupler. Stable QML with envelope duration as short as 10 ns and Q-switched repetition rate of 36 kHz was obtained. It is the shortest envelope duration as far as we know, and it is so short that it can be used as Q-switching pulses directly. At 6.9 W of the incident pump power, average output power of 1.24 W was achieved and the corresponding peak power and energy of a single Q-switched pulse were 3.44 kW and 34.4 mu J, respectively. The mode-locked pulses inside the Q-switched pulse envelope had a repetition rate of 780 MHz. (C) 2005 Elsevier B.V. All rights reserved.

Comparative studies of semiconductor saturable absorber mirror mode-locking dynamics in pulsed diode-end-pumped picosecond Nd:GdVO4 and Nd:YAG lasers

Ultrashort pulses were generated in passively mode-locked Nd:YAG and Nd:GdVO4 lasers pumped by a pulsed laser diode with 10-Hz repetition rate. Stable mode-locked pulse trains were produced with the pulse width of 10 ps. The evolution of the mode-locked pulse was observed in the experiment and was discussed in detail. Comparing the pulse evolutions of Nd:YAG and Nd:GdVO4 lasers, we found that the buildup time of the steady-state mode-locking with semiconductor saturable absorber mirrors (SESAMs) was relevant to the upper-state lifetime and the emission cross-section of the gain medium.