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报道激光二极管泵浦的掺钕氟磷酸钙固体激光器,该器件在重复频率为100Hz的准连续状态下运行,当耦合输出透过率为8%时,得到31%的斜效率,比较了FAP和YAG这两种介质的激光器的性能,理论分析得出的两者的阈值泵浦功率的相对值与实验结果相一致,并证实FAP是一种有前途的适合激光二极管泵浦的激光介质。 相似文献
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稀士元素掺杂单模光纤激光器是一种新颖的有源光纤器件.因其可与常规单模光纤、无源光纤器件(如耦合器、偏振器、滤波器和调制器等)等直接连接,使光源与光纤系统间的耦合损耗减至最小,又可实现全光纤网络.另外,它还可以满足某些光纤传感器在光源性能方面的特殊要求.因此,近年来国内外对这一有源光纤器件的研究工作方兴未艾.本文报道掺钕单模光纤的基础性研究.实验 实验中采用国产掺钕单膜光纤,钦的掺杂浓度为4OOppm,芯径为5.0μm,光纤长度 相似文献
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We present a detailed study of a superjunction(SJ) nanoscale partially narrow mesa(PNM) insulated gate bipolar transistor(IGBT) structure. This structure is created by combining the nanoscale PNM structure and the SJ structure together. It demonstrates an ultra-low saturation voltage(V_(ce(sat))) and low turn-off loss(E_(off)) while maintaining other device parameters. Compared with the conventional 1.2 k V trench IGBT, our simulation result shows that the V_(ce(sat))of this structure decreases to 0.94 V, which is close to the theoretical limit of 1.2 k V IGBT. Meanwhile, the fall time decreases from109.7 ns to 12 ns and the E off is down to only 37% of that of the conventional structure. The superior tradeoff characteristic between V_(ce(sat))and E_(off) is presented owing to the nanometer level mesa width and SJ structure. Moreover, the short circuit degeneration phenomenon in the very narrow mesa structure due to the collector-induced barriers lowering(CIBL) effect is not observed in this structure. Thus, enough short circuit ability can be achieved by using wide, floating P-well technique.Based on these structure advantages, the SJ-PNM-IGBT with nanoscale mesa width indicates a potentially superior overall performance towards the IGBT parameter limit. 相似文献
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木材导热系数对木结构建筑能耗精准预测具有重要意义,然而目前文献中的模型难以提供全面而准确的预测工具,且一些机器学习模型所考虑的因素和样本数有限。本文构建1941年至今含多种特征的导热系数数据库,并开发对比神经网络和迁移学习模型的预测精度。结果表明,结合迁移学习后,导热系数预测精度可提升23%以上,且迁移学习性能在0~0.3 W·m-1·K-1上精度提升明显,更适合于木结构等传热应用中。本文通过创新的模型参数微调迁移策略能为小样本、含大量缺失值的数据集和简单网络结构的导热系数预测提供思路。 相似文献
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Improvement on short-circuit ability of SiC super-junction MOSFET with partially widened pillar structure 下载免费PDF全文
Xinxin Zuo 《中国物理 B》2022,31(9):98502-098502
A novel 1200 V SiC super-junction (SJ) MOSFET with a partially widened pillar structure is proposed and investigated by using the two-dimensional numerical simulation tool. Based on the SiC SJ MOSFET structure, a partially widened P-region is added at the SJ pillar region to improve the short-circuit (SC) ability. After investigating the position and doping concentration of the widened P-region, an optimal structure is determined. From the simulation results, the SC withstand times (SCWTs) of the conventional trench MOSFET (CT-MOSFET), the SJ MOSFET, and the proposed structure at 800 V DC bus voltage are 15 μs, 17 μs, and 24 μs, respectively. The SCWTs of the proposed structure are increased by 60% and 41.2% in comparison with that of the other two structures. The main reason for the proposed structure with an enhanced SC capability is related to the effective suppression of saturation current at the high DC bias conditions by using a modulated P-pillar region. Meanwhile, a good Baliga's FOM ($BV^{2}/R_{\rm on}$) also can be achieved in the proposed structure due to the advantage of the SJ structure. In addition, the fabrication technology of the proposed structure is compatible with the standard epitaxy growth method used in the SJ MOSFET. As a result, the SJ structure with this feasible optimization skill presents an effect on improving the SC reliability of the SiC SJ MOSFET without the degeneration of the Baliga's FOM. 相似文献
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