85 research outputs found
All-linear time reversal by a dynamic artificial crystal
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 kāĻ/a and kā²=kā2ĻĻ/aāāĻ/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
Modulation of multiply scattered coherent light by ultrasonic pulses: An analytical model
Einfluss der Naturprozesse, waldbaulicher Massnahmen und Schutzmassnahmen auf die Erhaltung der Eibe im Naturreservat Pavelcovo, Slowakei | The effect of natural processes, silvicultural and protective measures on the conservation of common yew in the Nature Reserve Pavelcovo, Slovakia
Optical-frequency-comb generation with collinear acousto-optic diffraction: Theory and simulations
Should reference conditions be drawn from a single 10 ha plot? Assessing representativeness in a 10,000 ha oldāgrowth European beech forest
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