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固体激光棒中的热透镜效应对激光器的性能有很大的影响.在固体激光器的热稳腔的设计中也需要知道激光棒的热透镜焦距的数值,因此测量激光棒的热透镜焦距是必要的和有意义的.我们采用类似于文献[1]中的方法,测量了三种常用的固体激光棒在泵浦期间和泵浦后,各个时刻的热透镜焦距的数值.在单脉冲泵浦期间,红宝石、Nd:YAG和钕玻璃三种激光棒的热透镜焦距均为负值. 测量热透镜焦距的原理如图1所示.设He-Ne探测激光束的束腰半径为ω0,束腰和光阑离热透镜的距离分别为d1和d2。ωn和ωm分别为存在热透镜(例如负透镜)和无热透镜时探测激光束到达光… 相似文献
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在高斯光强近似下对泵浦LD光强分布模型进行修正,建立了LDA侧面泵浦固体激光介质内热源分布的数值模型。用有限元法计算模拟了三角均匀分布侧面泵浦结构激光棒瞬态温升过程及稳态温度分布情况。讨论比较了泵浦源的高斯强度近似和均匀强度近似下激光棒内温度分布情况,并对激光棒的类热透镜的焦距进行实验测量。实验和数值计算说明了LDA泵浦结构和冷却场的非均匀分布使实际温度场偏离均匀泵浦时的二次曲线分布模型,激光晶体热效应产生的类透镜会聚作用的不对称导致了激光器输出光束质量在x,y方向上的不同。 相似文献
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针对kJ级大能量钕玻璃固体脉冲激光器,对比研究了传统恒温水冷方式和采用加热控制的新型热管理技术下的激光棒温度分布情况。结果表明,采用新型热管理技术可大大降低棒内温度梯度,减小泵浦过程中的热效应,确保大能量激光输出;而且加热循环水的最佳升温值在单泵浦脉冲引起的激光棒平均温升值附近,使得径向温差最小,该最佳升温值与脉冲间隔时间有关,比如脉冲间隔15 s时,循环水在每个脉冲过后的最佳升温值为单泵浦脉冲引起的激光棒平均温升值的0.85倍;采用加热控制后水温和激光棒温度整体升高,因此在工作一个脉冲串后,必须恢复激光棒温度到初始状态,然后再进行下一个脉冲串工作。 相似文献
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分析了作为放大器应用的高功率二极管泵浦模块NdYAG圆棒的热效应,包括热透镜效应和热致双折射所引起的退偏效应及其补偿方法.在光路中加入合适的负透镜可以对特定工作条件下激光棒的热透镜进行较好的补偿;使用两个增益和荧光分布等参数完全一致的泵浦模块作为放大级,在其间加入90°石英旋转片和4F像传递系统可以较好的补偿热致双折射所引起的退偏效应.并且对以上方法进行了实验验证,取得了良好的补偿效果,提高了泵浦模块的提取效率和激光输出功率. 相似文献
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韩耀锋张若凡杨鸿儒段园园雷俊杰 《强激光与粒子束》2015,(6):24-31
建立了激光二极管阵列(LDA)侧面泵浦棒状Nd:YAG增益介质时变热效应理论计算模型。采用有限元Ansys软件模拟分析了脉冲LDA侧面泵浦大能量固体激光器的时变热效应特性。研究结果表明,所研究的脉冲LDA侧面泵浦大能量Nd:YAG激光器热效应具有时变特性,介质横截面内中心点处的稳态温度场分布随时间呈锯齿形周期变化,锯齿形变化频率为LDA泵浦频率,脉冲LDA泵浦参数对介质稳态温度场分布有较大影响。分析和计算了介质内热梯度、应力双折射以及激光晶体端面效应等导致的晶体热透镜焦距。计算表明,介质的热焦距主要来源于介质内温度梯度引起的热透镜焦距。 相似文献
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建立了激光二极管阵列(LDA)侧面泵浦棒状Nd:YAG增益介质时变热效应理论计算模型。采用有限元Ansys软件模拟分析了脉冲LDA侧面泵浦大能量固体激光器的时变热效应特性。研究结果表明,所研究的脉冲LDA侧面泵浦大能量Nd:YAG激光器热效应具有时变特性,介质横截面内中心点处的稳态温度场分布随时间呈锯齿形周期变化,锯齿形变化频率为LDA泵浦频率,脉冲LDA泵浦参数对介质稳态温度场分布有较大影响。分析和计算了介质内热梯度、应力双折射以及激光晶体端面效应等导致的晶体热透镜焦距。计算表明,介质的热焦距主要来源于介质内温度梯度引起的热透镜焦距。 相似文献
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In this work, the inhomogeneous equation of heat conduction was exactly solved by applying inhomogeneous boundary conditions
for laser crystals of aspect ratio=1 (aspect ratio=radius of the laser rod/length of the laser rod). We have shown that the
paraxial ray approximation leads the solution to be a function ofr
2
, that is, the approximation is equivalent to a situation in which a homogeneous pump source is used. The solution was then
used to derive expressions for the overall phase shift, focal length of the thermal lens and the end effect induced curvature
of the end face. The expressions were then applied to Nd:YAG laser medium. The result shows a meaningful correction of the
order of 0.001 cm to the focal length of Nd:YAG rod for 3 W source power and beam waist of 100 μm. 相似文献
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Xiao-lu Song Bing-bin Li Zhen Guo Shi-yu Wang De-fang Cai Jian-guo Wen 《Optics Communications》2009,282(24):4779-705
A numerical investigation is made on the thermal lensing and spherical aberration effect in an LD end-pumped Nd:YAG laser. Based on the finite element method (FEM), the laser rod temperature distribution is calculated and the focal length of the thermal lens is deduced, the influences of pump beam on the thermal lensing spherical aberration are mainly studied. The results show the thermal lens which focal length varied with the radial coordinate r is not an ideal lens. Given the heat dissipation boundary conditions, the radial dependent focal length will be shortened when the pump power raised or the waist radius of the pump beam reduced, meanwhile the radial differences of the focal length will decrease when the pump power increased. For a Super-Gaussian profile pump beam, the higher the exponent number, the more similar to flat top the pump beam is, and the less the radial differences of the focal length are. 相似文献
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A complete solution of the thermal effect for continuous wave laser diode array fiber coupled high pump power end pumped actively solid state laser is presented. In this paper, the thermal loading resulted from energy transfer up-conversion effect for laser operated under different pulse repetition frequency has been taken into account in the overall thermal effects. The thermal loading transfer the absorbed pump power into non-uniform temperature distribution in the laser rod, and thus results in thermal strain, thermal stress, thermal dispersion of index, and thermally induced diffraction losses. For a practical laser cavity configuration containing the internal optical elements, we use spherical aberration theory to give a better explanation of experimental results via calculating diffraction losses quantitatively. According to analysis of thermal focal length experimental data, the results show that our calculated value of thermal loading under fixed Nd3+ doped concentration laser crystal is not a constant but a function of pump power instead. The theoretical predicted curve of thermal focal length based on our model is in good agreement with experimental measurements. At low pump power, the thermal loading is a linear function varying with pump power, but it begins to saturate at pump powers exceeding 6 W. This phenomenon is consistent with our physical intuitions. 相似文献
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端侧面组合抽运DPL热透镜效应研究 总被引:1,自引:0,他引:1
通过数值计算发现:在端侧面组合抽运DPL中,晶体横截面上的温度分布接近于轴对称分布,并且端面抽运功率占有率越大,温度分布越接近于轴对称分布。将端侧面组合抽运DPL中的热效用等效薄透镜近似,给出了等效热透镜焦距的计算方法,分析了组合抽运引起的热透镜效应对基横模振荡光的光斑尺寸和衍射损耗的影响。在总抽运功率一定的情况下,端面抽运功率占有率的变化对热透镜焦距有一定的影响,占有率越大,热透镜焦距越长。提高端面抽运功率占有率,可在一定程度上减小热透镜效应对振荡光束尺寸和衍射损耗的影响。 相似文献
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建立了光强分布为高斯型的抽运光端面单程抽运时薄片激光器的温度模型, 实验测量了不同抽运功率下薄片介质表面的 温度分布、温度随时间的变化特性以及介质表面的温度差. 采用Hartmann法测量了薄片介质的热焦距. 考虑热焦距随抽运功率的变化, 基于四能级系统薄片激光器的速率方程组, 建立了薄片激光器热效应对输出功率影响的物理模型, 薄片激光器输入-输出功率曲线与实际相符. 所得结果对薄片激光器的设计和优化具有一定的指导意义. 相似文献
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Theoretical analysis and experimental research on thermal focal length of a YVO4/Nd:YVO4 composite crystal 下载免费PDF全文
This paper investigates the temperature field distribution and thermal focal length within a laser diode array (LDA) end-pumped YVO4/Nd:YVO4 rectangular composite crystal. A general expression of the temperature field distribution within the Nd:YVO4 rectangular crystal was obtained by analysing the characteristics of the Nd:YVO4 crystal and solving the Poisson equation with boundary conditions. The temperature field distributions in the Nd:YVO4 rectangular crystal for the YVO4/Nd:YVO4 composite crystal and the Nd:YVO4 single crystal are researched respec- tively. Calculating the thermal focal length within the Nd:YVO4 rectangular crystal was done by an analysis of the additional optical path differences (OPD) caused by heat, which was very identical with experimental results in this paper. Research results show that the maximum relative temperature on the rear face of the Nd:YVO4 crystal in the composite crystal is 150 K and the thermal focal length is 35.7 mm when the output power of the LDA is 22 W. In the same circumstances, the experimental value of the thermal focal length is 37.4 mm. So the relative error between the theoretical analysis and the experimental result is only 4.5%. With the same conditions, the thermal focal length of the Nd:YVO4 single crystal is 18.5 mm. So the relative rate of the thermal focal length between the YVO4/Nd:YVO4 crystal and the Nd:YVO4 crystal is 93%. So, the thermal stability of the output power and the beam quality of the YVO4/Nd:YVO4 laser is more advantageous than the laser with Nd:YVO4 single crystal. 相似文献
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Wenjie Xie Siu-Chung Tam Lam Yee-Loy Jingang Liu Hongru Yang Jianhui Gu Wilson Tan Feng Zhou 《Optics & Laser Technology》2000,32(3):1006
The pump energy distribution in a diode side-pumped solid-state laser, is an overlap of propagating Gaussian beams. A simple model has been developed to calculate the thermal focal length of a diode side-pumped solid-state laser, which is based on a thermal model with a Gaussian heat density in any cross section of a laser rod. It can be seen that as the waists of pump beams increase, the energy distribution tends to be uniform and the thermal focal length tends to be long, which means a smaller thermal focusing. 相似文献