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Generation of Ultrashort Light Bullets in Dispersive Kerr Media Using the Fourth—Order Dispersion—Dependent Spatiotemporal Instability
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A new method for generation of a train of ultrashort pulses or a sequence of ultrashort light bullets is proposed. This method is based on the fourth-order dispersion-dependent spatiotemporal instability in dispersive Kerr media. The repetition-rate of the generated bullets can be made quite large by increasing the corresponding spatial modulation frequency locating in the new instability region resulted from fourth-order dispersion. 相似文献
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研究了频率随时间变化的压缩态光场与二能级原子的相互作用,主要讨论了光场频率随时间作正弦调制和脉冲调制两种典型情况下,原子布居数反转随时间的演化特性。当光场频率随时间作正弦调制时,不仅光场频率调制,而且压缩态的压缩系数和压缩相位均对原子布居数反转的崩塌—回复过程有影响。当光场频率随时间作脉冲调制时,在原子布居数反转随时间演化过程中诱导出新的崩塌—回复过程,尤其在脉冲出现的区间内,原子布居数反转表现出持续的小幅快速振荡,这与压缩态的压缩系数无关。 相似文献
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(Ti,Al)N Film on Normalized T8 Carbon Tool Steel Prepared by Pulsed High Energy Density Plasma Technique
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Under optimized operating parameters, a hard and wear resistant (Ti,Al)N film is prepared on a normalized T8 carbon tool steel substrate by using pulsed high energy density plasma technique. Microstructure and composition of the film are analysed by x-ray diffraction, x-ray photoelectron spectroscopy, Auger electron spectroscopy and scanning electron microscopy. Hardness profile and tribological properties of the film are tested with nano- indenter and ring-on-ring wear tester, respectively. The tested results show that the microstructure of the film is dense ahd uniform and is mainly composed of (Ti,Al)N and A1N hard phases. A wide transition interface exists between the film and the normalized T8 carbon tool steel substrate. Thickness of the film is about lO00nm and mean hardness value of the film is about 26 GPa. Under dry sliding wear test conditions, relative wear resistance of the (Ti, Al)N film is approximately 9 times higher than that of the hardened T8 carbon tool steel reference sample. Meanwhile, the (Ti,Al)N film has low and stable friction coefficient compared with the hardened T8 carbon tool steel reference sample. 相似文献
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利用DDS器件设计高频雷达回波模拟器 总被引:5,自引:0,他引:5
基于双直接数字合成器Q2368芯片能实现任意波形的发生,采用单片机控制Q2368芯片,设计了PC机软件,使其通过串行通讯间接控制Q2368芯片产生各种波形,通过改变输出波形的时延与频率,模拟不同距离、不同速度的目标回波,代替实际目标检测雷达性能,节省了研制费用,缩短了雷达系统的研制周期。重点讨论了脉冲调制雷达和线性调频雷达的回波模拟器的设计与实施方案。 相似文献
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使用微电极并融合计算机控制的快速电势调制技术,推出了一类全新的暂态电化学多组份气体传感器--"电势脉冲调制型气体传感器”.与常规的稳态电化学气体传感器比较,优化了传感器性能,拓展了传感器新的功能和功能集成化. 相似文献
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