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王泽晖 《南昌大学学报(理科版)》2005,29(4):327-332
通过在差分方程上加一耗散项,根据其系数的选取得到只对短波起作用,而对长波没有影响的人工选择耗散法。数值算例表明该方法具有良好的激波捕获能力和可移植性。得到均匀非对称网格上的人工选择耗散法,并把人工选择耗散法推广到二维问题。 相似文献
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对含参变量函数的积分求导进行推广,得到了二重积分形式下的含参变量函数的积分求导公式以及在三维空间下的推广形式,并分析了其物理意义. 相似文献
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In this paper,we demonstrate an all-fiber linearly polarized fiber laser oscillator.The single polarization of the oscillator is achieved through the careful designing of the active fiber coiling.The relationship between fiber coiling diameter and polarization extinction ratio and optical efficiency is studied,whose results lead to an optimized system.The thermal management of the oscillator is also refined,which allows the oscillator to reach a maximum output power of44.1 W with an optical-to-optical efficiency of 57.9%.A high average polarization extinction ratio of 21.6 d B is achieved during a 2-hour stability test.The oscillator also owns a narrow 3-d B bandwidth of 0.1 nm,as well as near-diffraction-limit beam quality of M~2~ 1.14. 相似文献
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We study internal features of fiber fuse in a Yb-doped double-clad fiber. The samples of fiber fuse are acquired at the power level of 3 kW in an all-fiber forward-pumped master oscillator power amplifier configuration fiber laser that is built specially for fiber fuse analyses. At this high power level, drastic refractive-index redistribution arises in an expended high refractive index area around the bullet-shaped voids of fiber fuse. Electron spin resonance analyses on post-fiber-fuse samples of the Yb-doped double-clad fiber indicate rising Frenkel defect concentration, meanwhile showing a new resonance center that is different from the ones of the Ge-doped fibers studied previously. This new resonance center probably suggests the generation of Al-oxygen hole center, a kind of defect formed during the catastrophic fuse process. 相似文献
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同带抽运是目前实现高功率光纤激光器的有效手段.本文基于同带抽运方式,以国产25/250μm掺镱双包层光纤为增益光纤,构建了全光纤化的主控振荡器功率放大器.实验中采用的国产光纤是中国电子科技集团公司第四十六研究所采用化学气相沉积结合气相-液相复合掺杂工艺制备的,其Yb~(3+)离子的分布更均匀,吸收截面更大,吸收系数更高.实验中,在种子光功率为67.8 W、抽运总功率为3511 W的条件下,实现了3079 W的激光输出,斜效率为85.9%,光束质量M~2约为2.14,3dB带宽为1.4nm,这是目前基于国产光纤同带抽运方式实现的最高功率.理论和实验结果表明国产光纤制备技术不断成熟,已经具备承受高功率输出的能力.继续提高抽运功率,优化增益光纤长度,改良散热方式,国产光纤有望实现更高功率的激光输出. 相似文献
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