Advancements in Emerging Field of Plasmonics Yield Revolutionary Technologies
COLLEGE PARK, Md., Dec. 18 /PRNewswire-USNewswire/ -- Harry Potter may not
have talked much about plasmonics in J. K. Rowling's fantasy series, but
University of Maryland researchers are using this emerging technology to
develop an invisibility cloak that exists beyond the world of bespectacled
teenage wizards.
A research team at Maryland's A. James Clark School of Engineering comprised
of Professor Christopher Davis, Research Scientist Igor Smolyaninov, and
graduate student Yu-Ju Hung, has used plasmon technology to create the world's
first invisibility cloak for visible light. The engineers have applied the
same technology to build a revolutionary superlens microscope that allows
scientists to see details of previously undetectable nanoscale objects.
Generally speaking, when we see an object, we see the visible light that
strikes the object and is reflected. The Clark School team's invisibility
cloak refracts (or bends) the light that strikes it, so that the light moves
around and past the cloak, reflecting nothing, leaving the cloak and its
contents "invisible."
The invisibility cloak device is a two-dimensional pattern of concentric rings
created in a thin, transparent acrylic plastic layer on a gold film. The
plastic and gold each have different refractive properties. The structured
plastic on gold in different areas of the cloak creates "negative refraction"
effects, which bend plasmons--electron waves generated when light strikes a
metallic surface under precise circumstances--around the cloaked region.
This manipulation causes the plasmon waves to appear to have moved in a
straight line. In reality they have been guided around the cloak much as water
in a stream flows around a rock, and released on the other side, concealing
the cloak and the object inside from visible light. The invisibility that this
phenomenon creates is not absolutely perfect because of energy loss in the
gold film.
The team achieved this invisibility under very specialized conditions. The
researchers' cloak is just 10 micrometers in diameter; by comparison, a human
hair is between 50 to 100 micrometers wide. Also, the cloak uses a limited
range of the visible spectrum, in two dimensions. It would be a significant
challenge to extend the cloak to three dimensions because researchers would
need to control light waves both magnetically and electronically to steer them
around the hidden object. The technology initially may work only for small
objects of specific controlled shape.
The team also has used plasmonics to develop superlens microscopy technology,
which can be integrated into a conventional optical microscope to view
nanoscale details of objects that were previously undetectable.
The superlens microscope could one day image living cells, viruses, proteins,
DNA molecules, and other samples, operating much like a point-and-shoot
camera. This new technology could revolutionize the capability to view
nanoscale objects at a crucial stage of their development. The team believes
they can improve the resolution of their microscope images down to about 10
nanometers--one ten thousandth of the width of a human hair.
A large reason for the success of the group's innovations in both invisibility
and microscopy is that surface plasmons have very short wave lengths, and can
therefore move data around using much smaller-scale guiding structures than in
existing devices. These small, rapid waves are generated at optical
frequencies, and can transport large amounts of data. The group also has made
use of the unique properties of metamaterials, artificially structured
composites that help control electromagnetic waves in unusual ways using
plasmonic phenomena.
The diverse applications the group has derived from their plasmonics research
is an example of the ingenuity of researchers approaching new and dynamic
technologies that offer broad and unprecedented capabilities. The research has
attracted a great deal of attention within the scientific community, industry
and government agencies. Related plasmonics research offers applications for
military and computer chip technologies, which could benefit from the higher
frequencies and rapid data transfer rates that plasmons offer.
The team's research has been funded by the National Science Foundation and
Clark School Corporate Partner BAE Systems.
Smolyaninov and Davis have published an article in the journal Science about
their superlens microscope technology, titled "Magnifying Superlens in the
Visible Frequency Range." The group and their colleagues from Purdue
University will also soon publish a paper about their invisibility cloak
research. A manuscript describing the invisibility cloak is available online
at http://arxiv.org/abs/0709.2862.
About the A. James Clark School of Engineering
The Clark School of Engineering, situated on the rolling, 1,500-acre
University of Maryland campus in College Park, Md., is one of the premier
engineering schools in the U.S.
The Clark School's graduate programs are collectively the fastest rising in
the nation. In U.S. News & World Report's annual rating of graduate programs,
the school is 15th among public and private programs nationally, 9th among
public programs nationally and first among public programs in the mid-Atlantic
region. The School offers 13 graduate programs and 12 undergraduate programs,
including degree and certification programs tailored for working
professionals.
The school is home to one of the most vibrant research programs in the
country. With major emphasis in key areas such as communications and
networking, nanotechnology, bioengineering, reliability engineering, project
management, intelligent transportation systems and space robotics, as well as
electronic packaging and smart small systems and materials, the Clark School
is leading the way toward the next generations of engineering advances.
Visit the Clark School homepage at www.eng.umd.edu.
SOURCE A. James Clark School of Engineering
Ted Knight, +1-301-405-3596 (office), +1-410-703-4685 (cell),
teknight@umd.edu, or Missy Corley, +1-301-405-6501 (office), +1-804-398-8652
(cell), mcorley@umd.edu
