排序方式: 共有49条查询结果,搜索用时 15 毫秒
11.
A novel super-resolution near-field optical structure (super-RENS) with bismuth (Bi) mask layer is proposed in this paper. Static optical recording tests with and without super-RENS are carried out using a 650-nm semiconductor laser at recording powers of 14 and 7 mW with pulse duration of 100 ns. The recording marks are observed by high-resolution optical microscopy with a charge-coupled device (CCD) camera. The results show that the Bi mask layer can also concentrate energy into the center of a laser beam at low laser power similar to the traditional Sb mask layer. The results above are further confirmed by another Ar~+ laser system. The third-order nonlinear response induced by the plasma oscillation at the Bi/SiN interface during laser irradiation can be used to explain the phenomenon. The calculation results are basically consistent with our experimental results. 相似文献
12.
Self-phase modulation can efficiently shape the spectrum of an optical pulse propagating along an optical material with Kerr nonlinearity. In this work we show that a one-dimensional Kerr nonlinear photonic crystal can impose anomalous spectrum modulation to a high-power ultrashort light pulse. The spectrum component at the photonic band gap edge can be one order of magnitude enhanced in addition to the ordinary spectrum broadening due to self-phase modulation. The enhancement is strictly pinned at the band gap edge by changing the sample length, the intensity or central wavelength of the incident pulse. The phenomenon is attributed to band gap induced enhancement of light-matter interaction. 相似文献
13.
在磁光阱中利用冷原子温度低,多普勒展宽小的优势获得了窄线宽的里德堡电磁感应透明(EIT)谱峰,结合Autler-Townes分裂效应(EIT-AT分裂)分别测量了多个频率的微波电场强度.结果显示,EIT-AT分裂间距与微波电场强度呈很好的线性关系,EIT-AT分裂方法可测量的微波电场强度线性区的下限可达222μV/cm,这个下限比传统热原子蒸汽池中EIT-AT分裂线性区的下限5 mV/cm提高了大约22倍,这对极弱微波电场的绝对校准非常有帮助.我们进一步利用EIT共振处探测光透过率的变化测量微波电场强度,对应的最小测量值可以小于1μV/cm,相应的灵敏度可达到1μV·cm-1.Hz-1/2.这些结果展示了冷原子样品在微波电场测量及其绝对校准方面的优势. 相似文献
14.
在Y2O3-Al2O3-SiO2(YAS)钎料中添加TiO2(YT)和Si3N4(YN),并进行氮化硅陶瓷的连接,用四点弯曲方法测定不同连接工艺下的连接强度,并对连接界面进行SEM,EPMA和XRD分析,接头强度随着保温时间、连接温度的增加,而逐渐增加,在达到峰值后,连接强度逐渐降低。在YSA中添加TiO2,可以形成Si3N4/Y-Sialon玻璃+TiN/Tin/Y-Sialo玻璃的榜样经度层界面;而在YAS钎料中添加Si3N4,可以降低接头界面的热应力,改善接头强度,微观分析表明:接头强度的变化主要与界而面反应有关。 相似文献
15.
An all-optical phase detector by amplitude modulation of the local field in a Rydberg atom-based mixer 下载免费PDF全文
Xiu-Bin Liu 《中国物理 B》2022,31(9):90703-090703
Recently, a Rydberg atom-based mixer was developed to measure the phase of a radio frequency (RF) field. The phase of the signal RF (SIG RF) field is down-converted directly to the phase of a beat signal created by the presence of a local RF (LO RF) field. In this study, we propose that the Rydberg atom-based mixer can be converted to an all-optical phase detector by amplitude modulation (AM) of the LO RF field; that is, the phase of the SIG RF field is related to both the amplitude and phase of the beat signal. When the AM frequency of the LO RF field is the same as the frequency of the beat signal, the beat signal will further interfere with the AM of the LO RF field inside the atom, and then the amplitude of the beat signal is related to the phase of the SIG RF field. The amplitude of the beat signal and the phase of the SIG RF field show a linear relationship within the range of 0 to π/2 when the phase of the AM is set with a difference π/4 from the phase of the LO RF field. The minimum phase resolution can be as small as 0.6° by optimizing the experimental conditions according to a simple theoretical model. This study will expand and contribute to the development of RF measurement devices based on Rydberg atoms. 相似文献
16.
17.
18.
超高韧性水泥基复合材料(ultra high toughness cementitious composites, UHTCC)具有超高的韧性、良好的耐久性和优异的耗能效果,这些特性使得UHTCC在防护工程中具有广阔的应用前景。为了更好地研究UHTCC与纤维混凝土组合结构在二次打击条件下的抗侵彻性能,首先测量了UHTCC和聚乙烯醇纤维增强混凝土(polyvinl alcohol fiber reinforced concrete, FRC)的基本力学参数。然后采用25 mm口径的弹道滑膛炮对直径为750 mm、高为600 mm的圆柱形UHTCC靶体、FRC靶体、UHTCC-FRC组合靶体(UHTCC-FRC composite target)进行了弹体速度为550 m/s的二次侵彻试验,得到了弹体和三类靶体的破坏数据,包括弹体的侵彻深度、弹体的磨蚀、靶体迎弹面的开坑直径和面积、弹坑深度、迎弹面的裂纹数量以及裂纹最大宽度。在此基础上分析了骨料、结构形式和两次打击的间距对UHTCC-FRC组合靶体抗侵彻性能的影响。结果表明:相同试验条件下,与普通混凝土和超高性能混凝土相比,UHTCC能够有效的减小迎弹面的开坑直径,但会增加弹体侵彻深度;将50 mm的UHTCC置于组合靶的迎弹面可以有效地减少迎弹面的开坑直径;弹体二次侵彻深度大于弹体一次侵彻深度,靶体在二次冲击下的开坑面积小于靶体初次冲击下的开坑面积。 相似文献
19.
20.
准确评估战斗部侵彻爆炸作用下混凝土遮弹层的损伤破坏可为防护工程设计提供重要参考。首先基于Karagozian&Case(K&C)模型框架建立了新型混凝土动态损伤本构模型,其中强度面综合考虑了静水压力、Lode角、应变率和损伤;独立描述了拉伸和压缩损伤,并考虑了拉压之间的连续过渡以及剪切变形和体积压缩对损伤的贡献。随后,开展了半无限厚混凝土靶体的105 mm口径弹体侵彻爆炸联合作用试验。进一步通过对上述试验和已有有限厚混凝土靶板的预制孔埋置装药爆炸试验进行数值仿真分析,验证了所建立的本构模型、参数取值和有限元分析方法在描述混凝土动态阻力、损伤演化和开裂行为方面的准确性。最后,确定了SDB、WDB-43/B和BLU-109/B三种典型战斗部以声速侵彻爆炸普通混凝土的临界贯穿和临界震塌厚度。结果表明:SDB、WDB-43/B和BLU-109/B战斗部侵彻爆炸作用下混凝土的临界贯穿厚度分别为1.4、3.4和3.8 m,临界震塌厚度分别为3.6、6.3和8.3 m;由于携带炸药量的差异,不同战斗部侵彻爆炸下的临界贯穿和临界震塌厚度与侵彻深度的比值非定值,相应的比值范围分别为1.4... 相似文献