Researchers discover new limit of trapping light at the nanoscale

Date:
August 11, 2021
Source:
University of Southampton
Summary:
Physicists have reached a new threshold of light-matter coupling
at the nanoscale.



FULL STORY ========================================================================== Physicists from the University of Southampton and ETH Zu"rich have
reached a new threshold of light-matter coupling at the nanoscale.


==========================================================================
The international research, published this week in Nature Photonics,
combined theoretical and experimental findings to establish a fundamental limitation of our ability to confine and exploit light.

The collaboration focussed on photonic nano-antennas fabricated in ever reducing sizes on the top of a two-dimensional electron gas. The setup is commonly used in laboratories all over the world to explore the effect
of intense electromagnetic coupling, taking advantage of the antennas'
ability to trap and focus light close to electrons.

Professor Simone De Liberato, Director of the Quantum Theory and
Technology group at the University of Southampton, says: "The fabrication
of photonic resonators able to focus light in extremely small volumes
is proving a key technology which is presently enabling advances in
fields as different as material science, optoelectronics, chemistry,
quantum technologies, and many others.

"In particular, the focussed light can be made to interact extremely
strongly with matter, making electromagnetism non-perturbative. Light
can then be used to modify the properties of the materials it interacts
with, thus becoming a powerful tool for material science. Light can be effectively woven into novel materials." Scientists discovered that light could no longer be confined in the system below a critical dimension,
of the order of 250nm in the sample under study, when the experiment
started exciting propagating plasmons. This caused waves of electrons
to move away from the resonator and spill the energy of the photon.

Experiments performed in the group of Professors Je'ro^me Faist and
Giacomo Scalari at ETH Zu"rich had obtained results that could not
be interpreted with state-of-the-art understanding of light-matter
coupling. The physicists approached Southampton's School of Physics and Astronomy, where researchers led theoretical analysis and built a novel
theory able to quantitatively reproduce the results.

Professor De Liberato believes the newfound limits could yet be exceeded
by future experiments, unlocking dramatic technological advances that
hinge on ultra-confined electromagnetic fields.

"It has been said that proofs of impossibility are only proofs of a
lack of imagination," he explains. "This is not the first time that
a 'fundamental limit' on how tightly we can focus light has been
discovered. The most famous is the Abbe diffraction limit, from 19th
century German physicist Ernst Abbe, which says light can't be confined
in a volume smaller than a cubic wavelength.

"Nanophotonics is a very active and successful field of research that
is studying different ways to break out of Abbe limit. I think the next
step will be to use some ingenuity and look for novel ways to confine
light, bypassing both Abbe limit and the one we have just discovered." ========================================================================== Story Source: Materials provided by University_of_Southampton. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Shima Rajabali, Erika Cortese, Mattias Beck, Simone De Liberato,
Je'ro^me
Faist, Giacomo Scalari. Polaritonic nonlocality in light-matter
interaction. Nature Photonics, 2021; DOI: 10.1038/s41566-021-00854-3 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210811131525.htm

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