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Coiling technique is used to control the transverse mode of a large-mode-area (LMA) multimode fiber laser. By winding the fiber to a coil with different radius, high-order modes of a multimode fiber laser are suppressed one by one and finally 15.4-W single-transverse-mode output is achieved when the coil radius is 20 mm. It is found that as the coil radius decreases, the beam quality of a multimode fiber laser gets better but the slope efficiency drops for higher-order modes are discriminated. During the experiment, as the coil radius of multimode fiber changes, output characteristic of the laser has been measured. Meanwhile,the mode loss of different modes is calculated theoretically. It is proved that the experimental measured results fit well with the theoretically calculated results. 相似文献
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Zhao Z Bouchoule S Song J Galopin E Harmand JC Decobert J Aubin G Oudar JL 《Optics letters》2011,36(22):4377-4379
Near-transform-limited subpicosecond pulses at 1.56 μm were generated from an optically pumped InP-based vertical-external-cavity surface-emitting laser (VECSEL) passively mode-locked at 2 GHz repetition rate with a fast InGaAsNSb/GaAs semiconductor saturable absorber mirror (SESAM). The SESAM microcavity resonance was adjusted via a selective etching of phase layers specifically designed to control the magnitude of both the modulation depth and the intracavity group delay dispersion of the SESAM. Using the same VECSEL chip, we observed that the mode-locked pulse duration could be reduced from several picoseconds to less than 1 ps with a detuned resonant SESAM. 相似文献
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Harris公式和ab公式对超形变核转动带的适用性的比较 总被引:1,自引:1,他引:0
对A≈190区超变形转动带分别用Harris二参数公式和ab公式进行了系统分析.分析结果表明,与正常变形核动带的情况相似,Harris公式与实验有明显的系统偏离,而ab公式则与实验很接近,可以相当精确和方便地描述超变形转动带. 相似文献
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Xiangrui Yang Shichao Wu Yang Li Yu Huang Jinyan Lin Di Chang Shefang Ye Liya Xie Yuan Jiang Zhenqing Hou 《Chemical science》2015,6(3):1650-1654
Delicate mesoscopic architectures, bearing complex forms with multiple hierarchy levels, lead to significant functions in biogenic minerals. Herein, a bio-inspired approach was developed to fabricate comet-shaped assemblies of an anti-tumor drug – 10-hydroxycamptothecin (HCPT). The anti-solvent co-precipitation of HCPT and the excipient – PEG-b-PLGA – within the emulsifier leads to the immediate nucleation of comet bundles, followed by a secondary nucleation to generate the comet head, which is an assembly of nanofibers aligned almost in parallel. The continuous manufacturing furnishes drug–excipient hybrid particles with high drug-loading and a sustained drug release profile. This simple and efficient bio-inspired approach led to a promising sustained local drug delivery system, and could be extended to the fabrication of other functional organic materials bearing mesoscopic structural units. 相似文献
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A symmetric tensor, which has a symmetric nonnegative decomposition, is called a completely positive tensor. In this paper, we characterize the completely positive tensor as a truncated moment sequence, and transform the problem of checking whether a tensor is completely positive to checking whether its corresponding truncated moment sequence admits a representing measure, then present a semidefinite algorithm to solve it. If a tensor is not completely positive, a certificate for it can be obtained; if it is completely positive, a nonnegative decomposition can be obtained. 相似文献
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