334 research outputs found
Generation of pulse trains by current-controlled magnetic mirrors
The evolution of a spin-wave packet trapped between two direct
current-carrying wires placed on the surface of a ferrite film is observed by
Brillouin light scattering. The wires act as semi-transparent mirrors confining
the packet. Because the spin-wave energy partially passes through these
mirrors, trains of spin-wave packets are generated outside the trap. A
numerical model of this process is presented and applied to the case when the
current in the wires is dynamically controlled. This dynamical control of the
mirror reflectivity provides new functionalities interesting for the field of
spin-wave logic like that of a spin-wave memory cell.Comment: 4 pages, 3 figure
Scattering of backward spin waves in a one-dimensional magnonic crystal
Scattering of backward volume magnetostatic spin waves from a one-dimensional
magnonic crystal, realized by a grating of shallow grooves etched into the
surface of an yttrium-iron garnet film, was experimentally studied. Rejection
frequency bands were clearly observed. The rejection efficiency and the
frequency width of the rejection bands increase with increasing groove depth. A
theoretical model based on the analogy of a spin-wave film-waveguide with a
microwave transmission line was used to interpret the obtained experimental
results.Comment: 4 pages, 3 figure
Beam Wandering in the Atmosphere: The Effect of Partial Coherence
The effect of a random phase screen on laser beam wander in a turbulent
atmosphere is studied theoretically. The method of photon distribution function
is used to describe the photon kinetics of both weak and strong turbulence. By
bringing together analytical and numerical calculations, we have obtained the
variance of beam centroid deflections caused by scattering on turbulent eddies.
It is shown that an artificial distortion of the initial coherence of the
radiation can be used to decrease the wandering effect. The physical mechanism
responsible for this reduction and applicability of our approach are discussed.Comment: 16 pages, 5 figure
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