30 research outputs found
Arbitrary Engineering of Spatial Caustics with 3D-printed Metasurfaces
Caustics occur in diverse physical systems, spanning the nano-scale in
electron microscopy to astronomical-scale in gravitational lensing. As
envelopes of rays, optical caustics result in sharp edges or extended networks.
Caustics in structured light, characterized by complex-amplitude distributions,
have innovated numerous applications including particle manipulation,
high-resolution imaging techniques, and optical communication. However, these
applications have encountered limitations due to a major challenge in
engineering caustic fields with customizable propagation trajectories and
in-plane intensity profiles. Here, we introduce the compensation phase via
3D-printed metasurfaces to shape caustic fields with curved trajectories in
free space. The in-plane caustic patterns can be preserved or morphed from one
structure to another during propagation. Large-scale fabrication of these
metasurfaces is enabled by the fast-prototyping and cost-effective two-photon
polymerization lithography. Our optical elements with the ultra-thin profile
and sub-millimeter extension offer a compact solution to generating caustic
structured light for beam shaping, high-resolution microscopy, and
light-matter-interaction studies
The spectral density of TGSMA beams
The animated representation of the full propagation of spectral densit
The spectral density of TGSMA beams
The animated representation of the full propagation of spectral densit
The degree of coherence of TGSMA beams
The animated representation of the full propagation of DO
The degree of cherence of TGSMA beams
The animated representation of the full propagation of DO
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Cross-spectral density matrix of a random electromagnetic beam propagating through an apertured axially nonsymmetrical optical system
Using the fact that a hard-edged rectangular aperture function can be approximated by a two-dimensional multi-Gaussian series, analytic formulas for the elements of the cross-spectral density matrix of a random electromagnetic beam truncated by a rectangular aperture and passing through an axially nonsymmetrical optical system is derived. The analysis is illustrated by numerical examples relating to changes in the spectral degree of polarization of electromagnetic Gaussian Schell-model beams propagating through free space, focal system and dual-focus system. In particular, the effect of the size of the hard aperture on the spectral degree of polarization of the beam along its optical axis is discussed
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Application of correlation-induced spectral changes to inverse scattering
It is shown how the phenomenon of correlation-induced spectral changes generated on scattering of a polychromatic plane wave on a spatially homogeneous random medium may be used to determine the correlation function of the scattering potential of the medium.</p
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Changes in the statistical properties of stochastic anisotropic electromagnetic beams on propagation in the turbulent atmosphere
We report analytic formulas for the elements of the e 2 X 2 cross-spectral density matrix of a stochastic electromagnetic anisotropic beam propagating through the turbulent atmosphere with the help of vector integration. From these formulas the changes in the spectral density (spectrum), in the spectral degree of polarization, and in the spectral degree of coherence of such a beam on propagation are determined. As an example, these quantities are calculated for a so-called anisotropic electromagnetic Gaussian Schell-model beam propagating in the isotropic and homogeneous atmosphere. In particular, it is shown numerically that for a beam of this class, unlike for an isotropic electromagnetic Gaussian Schell-model beam, its spectral degree of polarization does not return to its value in the source plane after propagating at sufficiently large distances in the atmosphere. It is also shown that the spectral degree of coherence of such a beam tends to zero with increasing distance of propagation through the turbulent atmosphere, in agreement with results previously reported for isotropic beams.</p