Through the development of a new nanomanufacturing technique, Odom and
her colleagues have succeeded in making gold films with virtually
infinite arrays of circular perforations as small as 100 nanometers in
diameter - 500 to 1,000 times smaller than the diameter of a human
hair. On a magnified scale, these perforated gold films look like
Swiss cheese except the perforations are well-ordered and can spread
over macroscale distances. The researchers� ability to make these
optical metamaterials inexpensively and on large wafers or sheets is
what sets this work apart from other techniques.
�One of the biggest problems with nanomaterials has always been their
�scalability,�� said Odom, associate professor of chemistry in the
Weinberg College of Arts and Sciences. �It�s been very difficult or
prohibitively expensive to pattern them over areas larger than about
one square millimeter. This research is exciting not only because it
demonstrates a new type of patterning technique that is cheap, but
also one that can produce very high quality optical materials with
interesting properties.�
For example, if the perforations or holes are patterned into
microscale �patches,� they show dramatically different transmission
behavior of light compared to an infinite array of holes. The patches
appear to focus light while the infinite arrays do not.
Moreover, their optical transmission can be altered simply by changing
the geometry of perforations rather than having to �cook� a new
composition of materials. This feature makes them very attractive in
terms of tuning their behavior to a given need with ease. These
materials also can be superior as optical sensors, and they open the
possibility of ultra-small sources of light. Furthermore, given their
precise organization, they can serve as templates for making their own
clones or for making other ordered structures at the nanoscale, such
as arrays of nanoparticles.
�This work is exactly the kind of high-risk, high-potential
transformative research NSF�s Division of Materials Research is
interested in supporting,� said Harsh Deepak Chopra, program manager
at the National Science Foundation (NSF), which funded the research.
�The early results are extremely promising and suggest a whole new
generation of optical devices.�
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