Metamaterials research challenges fundamental limits in photonics

Date:
August 10, 2021
Source:
Cornell University
Summary:
Researchers are proposing a new way to modulate both the absorptive
and the refractive qualities of metamaterials in real time,
and their findings open intriguing new opportunities to control,
in time and space, the propagation and scattering of waves for
applications in various areas of wave physics and engineering.



FULL STORY ========================================================================== Cornell researchers are proposing a new way to modulate both the
absorptive and the refractive qualities of metamaterials in real time,
and their findings open intriguing new opportunities to control, in time
and space, the propagation and scattering of waves for applications in
various areas of wave physics and engineering.


==========================================================================
The research published in the journal Optica, "Spectral causality and
the scattering of waves," is authored by doctoral students Zeki Hayran
and Aobo Chen, M.S. '19, along with their adviser, Francesco Monticone, assistant professor in the School of Electrical and Computer Engineering
in the College of Engineering.

The theoretical work aims to expand the capabilities of metamaterials to
absorb or refract electromagnetic waves. Previous research was limited
to modifying either absorption or refraction, but the Monticone Research
Group has now shown that if both qualities are modulated in real time,
the effectiveness of the metamaterial can be greatly increased.

These temporally modulated metamaterials, sometimes referred to as
"chrono- metamaterials" may open unexplored opportunities and enable technological advances in electromagnetics and photonics.

"What we demonstrate," Monticone said, "is that if you modulate both
properties in time, you manage to absorb electromagnetic waves much more efficiently than in a static structure, or in a structure in which you
modulate either one of these two degrees of freedom individually. We
combined these two aspects together to create a much more effective
system." The findings may lead to the development of new metamaterials
with wave absorption and scattering properties that far outperform what is currently available. For example, a broadband absorber has to be thicker
than a certain value to be effective, but the material thickness will
limit the applications of the design.



==========================================================================
"To decrease the thickness and increase the bandwidth of such an absorber,
you have to overcome the limitations of conventional materials,"
Hayran said. "One of the ways to bypass these limitations is through
temporally modulating the structure." The aim of Monticone's group
is to open new areas of research to produce increasingly efficient
practical applications.

"What we are trying to do is not incremental changes to the technology," Monticone said. "We want disruptive changes. That's really what
motivates us.

So how can we make a dramatic improvement to the technology, not just an incremental improvement? To do that, very often, you have to go back to
the fundamentals." The new research pushes the limits of electromagnetic
wave absorption by using another degree of freedom, which is modulation
in time, something not typically done in this area, but now receiving increasing research attention.

With a new theoretical underpinning in place, experimentally implementing temporal modulations of this kind is the challenge for further research. A physical experiment would first need to design a mechanism to control
the modulation of absorptive and refractive qualities of a material over
time, which might include laser beams or microwave components.

The ideas have direct implications for several applications,
such as broadband radar absorption and temporal invisibility and
cloaking. Applications could also extend to other domains of wave physics
such as acoustics and elastodynamics.

"Our findings, and the exciting results by other researchers working
in this area, highlight the many opportunities offered by time-varying metamaterials for both classical and quantum electromagnetics and
photonics," Monticone said.

This research is supported by the Air Force Office of Scientific Research
and the National Science Foundation. Additional support is provided
through the Fulbright Foreign Student Program of the U.S. Department
of State.

========================================================================== Story Source: Materials provided by Cornell_University. Original written
by Eric Laine. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Zeki Hayran, Aobo Chen, Francesco Monticone. Spectral causality
and the
scattering of waves. Optica, 2021; 8 (8): 1040 DOI:
10.1364/OPTICA.423089 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210810130755.htm

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