Tailored light inspired by nature
Researchers develop for the first time light fields using caustics that
do not change during propagation

Date:
July 29, 2020
Source:
University of Mu"nster
Summary:
An international research team has develop for the first time light
fields using caustics that do not change during propagation. With
the new method, the physicists cleverly exploit light structures
that can be seen in rainbows or when light is transmitted through
drinking glasses.



FULL STORY ========================================================================== Modern applications as high resolution microsopy or micro- or
nanoscale material processing require customized laser beams that do
not change during propagation. This represents an immense challenge
since light typically broadens during propagation, a phenomenon known
as diffraction. So-called propagation-invariant or non-diffracting
light fields therefore do not seem possible at first glance. If it were possible to produce them, they would enable new applications such as
light disk microscopy or laser-based cutting, milling or drilling with
high aspect ratios.


==========================================================================
An international research team from the Universities of Birmingham
(UK), Marseille (France) and Mu"nster (Germany) has now succeeded for
the first time to create arbitrary nondiffracting beams. "We implement
an approach inspired by nature, in which any desired intensity structure
can be specified by its boundaries," explains one of the authors of the
study, Prof. Cornelia Denz from the Institute of Applied Physics at the University of Mu"nster. The authors cleverly exploit light structures
that can be seen in rainbows or when light is transmitted through drinking glasses: spectacular ray structures named caustics. They are bright focus
lines that overlap, and thereby building networks that can be exploited
for nondiffracting propagation. The team developed a method to use these caustics as a basis for the generation of arbitrary structures, and has
thus created an intelligent manipulation of ray propagation. In this way, countless new types of laser beams can be formed on the micrometer scale, opening up completely new perspectives in optical materials processing, multidimensional signal transmission or advanced high resolution imaging.

Only some years ago it was possible to realize a few light fields that
exhibit these non-diffracting properties, even though the theoretical
idea is older: Concentric ring structures like the Bessel beam could be produced in a propagation-invariant way. The theory predicts a whole
class of beams whose transverse shape is generated on elliptical or
parabolic trajectories and represent natural solutions of the wave
equation. Although there has long been a need for such customized light
beams with these properties, they have hardly been produced experimentally because the invariance of the transverse intensity structure must be
maintained during propagation.


========================================================================== Story Source: Materials provided by University_of_Mu"nster. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Alessandro Zannotti, Cornelia Denz, Miguel A. Alonso, Mark
R. Dennis.

Shaping caustics into propagation-invariant light. Nature
Communications, 2020; 11 (1) DOI: 10.1038/s41467-020-17439-3 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200729114725.htm

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