Observation of wave packet distortion during a negative-group-velocity transmission.
Observation of wave packet distortion during a negative-group-velocity transmission.
复制标题
负群速度传输过程中波包畸变的观察
DOI：
10.1038/srep08100
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发表时间：
2015-01-29
影响因子：
4.6
通讯作者：
Ran L
中科院分区：
文献类型：
--
作者：
Ye D;Salamin Y;Huangfu J;Qiao S;Zheng G;Ran L
在物理学中，因果关系是由热力学第二定律产生的一个基本假设。它指出，一个事件的原因先于其结果。在电磁学的背景下，相对论性的因果关系将电磁波包所携带的信息的速度上限限制在自由空间中的光速(c)。在异常色散介质（ADM）中，研究表明，波包以超光速甚至负群速度传播。然而，索默菲尔德和布里渊指出，这种波包的“前端”，即索默菲尔德前体的起始点，总是以同样的速度传播。本文研究了半正弦波包的负群速传输。实验观察了微波条件下被动人工ADM中以负群速传播的调制波包的波前和畸变。与以往关于超光速高斯包传播的文献不同，我们观察到了非超光速波前的强畸变正弦包。这一结果与Brillouin的断言一致，即看似超光速的波包的严重畸变使得群速度的定义在异常色散区域具有物理意义。
In Physics, causality is a fundamental postulation arising from the second law of thermodynamics. It states that, the cause of an event precedes its effect. In the context of Electromagnetics, the relativistic causality limits the upper bound of the velocity of information, which is carried by electromagnetic wave packets, to the speed of light in free space (c). In anomalously dispersive media (ADM), it has been shown that, wave packets appear to propagate with a superluminal or even negative group velocity. However, Sommerfeld and Brillouin pointed out that the “front” of such wave packets, known as the initial point of the Sommerfeld precursor, always travels atc. In this work, we investigate the negative-group-velocity transmission of half-sine wave packets. We experimentally observe the wave front and the distortion of modulated wave packets propagating with a negative group velocity in a passive artificial ADM in microwave regime. Different from previous literature on the propagation of superluminal Gaussian packets, strongly distorted sinusoidal packets with non-superluminal wave fronts were observed. This result agrees with Brillouin's assertion, i.e., the severe distortion of seemingly superluminal wave packets makes the definition of group velocity physically meaningless in the anomalously dispersive region.
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影响因子：
4.6
作者：
Ye, Dexin;Zheng, Guoan;Wang, Jingyu;Wang, Zhiyu;Qiao, Shan;Huangfu, Jiangtao;Ran, Lixin
通讯作者：
Ran, Lixin
影响因子：
2.4
作者：
Sommerfeld, A
通讯作者：
Sommerfeld, A
影响因子：
56.9
作者：
Dolling, G;Enkrich, C;Linden, S
通讯作者：
Linden, S
影响因子：
64.8
作者：
Wang, LJ;Kuzmich, A;Dogariu, A
通讯作者：
Dogariu, A
影响因子：
1.8
作者：
Hickmann, J. M.;Alencar, M. A. R. C.;Souza, S. T.
通讯作者：
Souza, S. T.