269 research outputs found
Airy wave packets accelerating in space-time
Although diffractive spreading is an unavoidable feature of all wave
phenomena, certain waveforms can attain propagation-invariance. A
lesser-explored strategy for achieving optical selfsimilar propagation exploits
the modification of the spatio-temporal field structure when observed in
reference frames moving at relativistic speeds. For such an observer, it is
predicted that the associated Lorentz boost can bring to a halt the axial
dynamics of a wave packet of arbitrary profile. This phenomenon is particularly
striking in the case of a self-accelerating beam -- such as an Airy beam --
whose peak normally undergoes a transverse displacement upon free-propagation.
Here we synthesize an acceleration-free Airy wave packet that travels in a
straight line by deforming its spatio-temporal spectrum to reproduce the impact
of a Lorentz boost. The roles of the axial spatial coordinate and time are
swapped, leading to `time-diffraction' manifested in self-acceleration observed
in the propagating Airy wave-packet frame.Comment: 5 pages, 4 figure
Interferometry-based modal analysis with finite aperture effects
We analyze the effects of aperture finiteness on interferograms recorded to
unveil the modal content of optical beams in arbitrary basis using generalized
interferometry. We develop a scheme for modal reconstruction from
interferometric measurements that accounts for the ensuing clipping effects.
Clipping-cognizant reconstruction is shown to yield significant performance
gains over traditional schemes that overlook such effects that do arise in
practice. Our work can inspire further research on reconstruction schemes and
algorithms that account for practical hardware limitations in a variety of
contexts
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