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All-linear time reversal by a dynamic artificial crystal.

Chumak AV, Tiberkevich VS, Karenowska AD, Serga AA, Gregg JF, Slavin AN, Hillebrands B - Nat Commun (2010)

Bottom Line: 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.As a result, a linear coupling between wave components with wave vectors k≈π/a and k'=k-2π/a≈-π/a is produced, which leads to spectral inversion, and thus to the formation of a time-reversed wave packet.

View Article: PubMed Central - PubMed

Affiliation: Fachbereich Physik and Forschungszentrum OPTIMAS, Technische Universität Kaiserslautern, Kaiserslautern 67663, Germany. chumak@physik.uni-kl.de

ABSTRACT
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≈π/a and k'=k-2π/a≈-π/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.

No MeSH data available.


Related in: MedlinePlus

Experimental demonstration of time reversal by the dynamic magnonic crystal.A train of two spin-wave pulses (70 ns wide and spacing 40 ns) with carrier frequency fS=6,500 MHz was applied to the input antenna. The applied signals shown (green) are the envelopes of those supplied by the microwave generator. (a) The transmitted spin-wave signals with no current applied to the DMC meander structure appear after a delay of ∼300 ns (upper frame, blue). When the first of the two input pulses is switched off, the first transmitted pulse is absent (middle frame) and the same is true for the second pulse (lower frame). (b) The reflected spin-wave signals obtained after a brief interval of magnetic field modulation within the DMC (shaded area shows the time interval of the current pulse applied to the meander structure). In the case that two spin-wave pulses are applied, two corresponding reflected pulses are observed (upper frame, red). When the first of the two pulses is switched off, the second reflected pulse is absent (middle frame), and vice versa (lower frame), confirming time reversal.
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f4: Experimental demonstration of time reversal by the dynamic magnonic crystal.A train of two spin-wave pulses (70 ns wide and spacing 40 ns) with carrier frequency fS=6,500 MHz was applied to the input antenna. The applied signals shown (green) are the envelopes of those supplied by the microwave generator. (a) The transmitted spin-wave signals with no current applied to the DMC meander structure appear after a delay of ∼300 ns (upper frame, blue). When the first of the two input pulses is switched off, the first transmitted pulse is absent (middle frame) and the same is true for the second pulse (lower frame). (b) The reflected spin-wave signals obtained after a brief interval of magnetic field modulation within the DMC (shaded area shows the time interval of the current pulse applied to the meander structure). In the case that two spin-wave pulses are applied, two corresponding reflected pulses are observed (upper frame, red). When the first of the two pulses is switched off, the second reflected pulse is absent (middle frame), and vice versa (lower frame), confirming time reversal.

Mentions: Figure 4a shows—for reference—time profiles of input (green) and transmitted (blue) signals detected in the absence of DMC activation. Here, if the first spin-wave pulse is switched off (middle frame), the first pulse in the transmitted signal disappears. Similarly, the switching off of the second pulse (lower frame) leads to the disappearance of the second transmitted envelope.


All-linear time reversal by a dynamic artificial crystal.

Chumak AV, Tiberkevich VS, Karenowska AD, Serga AA, Gregg JF, Slavin AN, Hillebrands B - Nat Commun (2010)

Experimental demonstration of time reversal by the dynamic magnonic crystal.A train of two spin-wave pulses (70 ns wide and spacing 40 ns) with carrier frequency fS=6,500 MHz was applied to the input antenna. The applied signals shown (green) are the envelopes of those supplied by the microwave generator. (a) The transmitted spin-wave signals with no current applied to the DMC meander structure appear after a delay of ∼300 ns (upper frame, blue). When the first of the two input pulses is switched off, the first transmitted pulse is absent (middle frame) and the same is true for the second pulse (lower frame). (b) The reflected spin-wave signals obtained after a brief interval of magnetic field modulation within the DMC (shaded area shows the time interval of the current pulse applied to the meander structure). In the case that two spin-wave pulses are applied, two corresponding reflected pulses are observed (upper frame, red). When the first of the two pulses is switched off, the second reflected pulse is absent (middle frame), and vice versa (lower frame), confirming time reversal.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3105294&req=5

f4: Experimental demonstration of time reversal by the dynamic magnonic crystal.A train of two spin-wave pulses (70 ns wide and spacing 40 ns) with carrier frequency fS=6,500 MHz was applied to the input antenna. The applied signals shown (green) are the envelopes of those supplied by the microwave generator. (a) The transmitted spin-wave signals with no current applied to the DMC meander structure appear after a delay of ∼300 ns (upper frame, blue). When the first of the two input pulses is switched off, the first transmitted pulse is absent (middle frame) and the same is true for the second pulse (lower frame). (b) The reflected spin-wave signals obtained after a brief interval of magnetic field modulation within the DMC (shaded area shows the time interval of the current pulse applied to the meander structure). In the case that two spin-wave pulses are applied, two corresponding reflected pulses are observed (upper frame, red). When the first of the two pulses is switched off, the second reflected pulse is absent (middle frame), and vice versa (lower frame), confirming time reversal.
Mentions: Figure 4a shows—for reference—time profiles of input (green) and transmitted (blue) signals detected in the absence of DMC activation. Here, if the first spin-wave pulse is switched off (middle frame), the first pulse in the transmitted signal disappears. Similarly, the switching off of the second pulse (lower frame) leads to the disappearance of the second transmitted envelope.

Bottom Line: 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.As a result, a linear coupling between wave components with wave vectors k≈π/a and k'=k-2π/a≈-π/a is produced, which leads to spectral inversion, and thus to the formation of a time-reversed wave packet.

View Article: PubMed Central - PubMed

Affiliation: Fachbereich Physik and Forschungszentrum OPTIMAS, Technische Universität Kaiserslautern, Kaiserslautern 67663, Germany. chumak@physik.uni-kl.de

ABSTRACT
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≈π/a and k'=k-2π/a≈-π/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.

No MeSH data available.


Related in: MedlinePlus