期刊
NATURE COMMUNICATIONS
卷 1, 期 -, 页码 -出版社
NATURE PUBLISHING GROUP
DOI: 10.1038/ncomms1142
关键词
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资金
- Deutsche Forschungsgemeinschaft [SE 1771/1]
- USA National Science Foundation
- U.S. Army TARDEC, RDECOM [W56HZW-09-PL564]
- Magdalen College, Oxford
- Directorate For Engineering
- Div Of Electrical, Commun & Cyber Sys [1001815] Funding Source: National Science Foundation
The time reversal of pulsed signals or propagating wave packets has long been recognized to have profound scientific and technological significance. Until now, all experimentally verified time-reversal mechanisms have been reliant upon nonlinear phenomena such as four-wave mixing. In this paper, we report the experimental realization of all-linear time reversal. The time-reversal mechanism we propose is based on the dynamic control of an artificial crystal structure, and is demonstrated in a spin-wave system using a dynamic magnonic crystal. The crystal is switched from an homogeneous state to one in which its properties vary with spatial period a, while a propagating wave packet is inside. As a result, a linear coupling between wave components with wave vectors k approximate to pi/a and k' = k - 2 pi/a approximate to - pi/a is produced, which leads to spectral inversion, and thus to the formation of a time-reversed wave packet. The reversal mechanism is entirely general and so applicable to artificial crystal systems of any physical nature.
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