Pulsed pump: Thermal effects in solid state lasers under super-Gaussian pulses

Solid state laser (SSL) powers can be realistically scaled when pumped by a real, efficient and multimode pulse. In this work, a fourth-order super-Gaussian pulse was assumed as a pump for SSL’s and a complete analytical expression for the thermal phase shift is given. Moreover, the focal length of thermal lens in paraxial ray approximation regime was studied. The results when applied to a Ti: sapphire crystal show an appreciable correction for abberation compared to a top-hat pulse.     

二极管泵浦激光器中泵浦光分布对激光器模式影响程度的计算方法

在激光器中,通常泵浦光呈不均匀分布,由此引起介质的增益也相应地出现不均匀分布,导致振荡光通过增益区时其分布发生变化。提出一种计算不均匀的泵浦光分布对于激光器内振荡光模式的影响程度,可以近似获得振荡光对原来场分布偏离的百分比的方法。在此基础上,对准连续运转的三向侧面泵浦激光器进行研究,分析不均匀泵浦光分布对振荡光场影响的规律。结果表明:当泵浦功率增加或谐振腔内损耗增加时,振荡光通过增益区时对原来分布的偏离程度也同时增加,呈单调变化关系;泵浦光不均匀分布对振荡光场的影响,与其沿振荡光轴向上的分布无关,仅仅取决于其在与振荡光垂直方向上的不均匀分布程度。通过计算还获得了此类效应的数量级,在2 000 W泵浦功率条件下,这种影响仅使振荡光偏离理想分布不到4%,而泵浦功率达到6 000 W时这种偏离则高达20%以上。     

应用于地形匹配导航的激光高度计设计

为解决基于雷达高度表探测的地形匹配导航系统探测精度不高、易受电子干扰影响而失效、且在跨海飞行时无法导航的难题,设计了一种激光高度计来代替雷达高度表进行地形探测。采用二极管泵浦固体激光器技术设计激光发射装置,输出近红外/蓝绿双波长激光,既可以测量陆地地形高度,又可以穿透海水探测海底地形;并根据激光高度计拟达到的性能指标选择合适的光电探测器,优化设计了光学系统、扫描系统和信号处理系统。所设计的激光高度计具有体积小、重量轻、高重频、探测灵敏度高、抗电磁干扰能力强等特点。     

Laser spectroscopy of optical centers in borosilicophosphate glass, coactivated by erbium and ytterbium ions

Based on analysis of the laser emission spectra of borosilicophosphate glass, coactivated by Er³⁺ and Yb³⁺ ions, we have determined the structure of the Stark splitting of the luminescence band for the erbium ion in the 1.5 μm region (the transition ⁴I_13/2 → ⁴I_15/2). In the wavelength interval 1532–1547 nm, we identified 12 sets of lines belonging to different types of optical centers of predominantly cubic symmetry. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 4, pp. 483–487, July–August, 2006.     

Judd--Ofelt analysis of spectra and experimental evaluation of laser performance of Tm3+ doped Lu2SiO5 crystal

This paper reports that the Tm^3＋：Lu2SiO5 （Tm：LSO） crystal is grown by Czochralski technique. The roomtemperature absorption spectra of Tm：LSO crystal are measured on a b-cut sample with 4 at.% thulium. According to the obtained Judd-Ofelt intensity parameters Ω2=9.3155×10^-20 cm^2, Ω4=8.4103×10^-20 cm^2, Ω6=1.5908×10^-20 cm^2, the fluorescence lifetime is calculated to be 2.03 ms for ^3F4 → ^3H6 transition, and the integrated emission cross section is 5.81×10^-18 cm^2. Room-temperature laser action near 2μm under diode pumping is experimentally evaluated in Tm：LSO. An optical-optical conversion efficiency of 9.1% and a slope efficiency of 16.2% are obtained with continuouswave maximum output power of 0.67 W. The emission wavelengths of Tm：LSO laser are centred around 2.06μm with spectral bandwidth of -13.6 nm.     

脉冲激光二极管泵浦调Q激光器泵浦时间特性研究

从调Q激光器的速率方程出发,对脉冲激光二极管泵浦的调Q激光器在不同泵浦功率及不同透过率情况下的最佳泵浦时间进行了理论分析。计算结果表明,在透过率为20%,腔内损耗为0.05的条件下,1—3倍阈值泵浦功率时,最高效率对应的最佳泵浦时间为1—1.5倍Nd∶YAG荧光寿命;7倍阈值泵浦功率及以上时,最佳泵浦时间约为荧光寿命的一半或者更短。在脉冲泵浦能量相同时,采用较短的泵浦时间(即泵浦功率较高),调Q输出的能量转换效率较高。     

Diode-pumped Solid-state Cr4+:Nd:YAG/KTP Green Laser

A diode-pumped solid-state Cr4+:Nd:YAG/KTP green laser with intracavity second harmonic generation is reported. Stable quasi-cw output of 1.03 W in average power, 100 kHz of repetition rate and about 25 ns of pulse width were obtained. Repetition rate and pulse width were studied experimentally and analyzed under different conditions.     

Design of LD in-band direct-pumping side surface polished micro-rod Nd:YVO_4 laser

To diminish the thermal load, two ways, that is, in-band direct pumping and micro-rod crystal, could be adopted at the same time. The efficiency of LD in-band direct-pumping side surface polished micro-rod Nd:YVO_4 laser is numerically analyzed. By optimizing parameters such as crystal length, laser mode radius, pump beam radius, doping concentration and crystal cross-section size, the overall efficiency can reach over 50%. It is found that with micro-rod crystal implemented in the laser oscillator, high overall efficiency LD in-band direct-pumping Nd:YVO_4 laser could be realized. High efficiency combined with low thermal load makes this laser an outstanding scheme for building high-power Nd:YVO_4 lasers.     

GO法在固体激光器可靠性分析中的应用

对高功率半导体泵浦固体激光器(DPL)系统的可靠性进行了分析,根据GO法的原理构建了DPL系统的GO图;利用GO法计算公式,得到了系统故障率和平均无故障工作时间等重要可靠性指标。结果符合实验室经验值。最后分析了各部件的故障率的重要度,讨论了改善高功率DPL系统可靠性的措施,对系统的使用和维修等工作具有参考意义。     

激光二极管抽运的高重频高平均功率Nd:YAG激光器

搭建了一台高重复频率、高峰值功率、高平均功率的激光器. 激光器主要包括三部分: 单纵模光纤种子源、激光二极管阵列抽运的Nd:YAG再生放大器和四程放大器. 系统获得了平均功率11 W、重复频率100 Hz、脉冲能量112 mJ、脉宽500 ps–2 ns可调的激光输出, 工作波长1064 nm. 输出光束口径6.8 mm, 1.5倍衍射极限, 近场光强近平顶分布, 能量稳定性为0.72%. 关键词： 激光二极管抽运 高重复频率 高峰值功率 高平均功率