Search
Menu
Deposition Sciences Inc. - Difficult Coatings - LB - 8/23

Plasmonic Absorbers Capture Specific Wavelengths

Facebook X LinkedIn Email
An experimental fabrication technique has created perfect absorbers for small bands of the electromagnetic spectrum from visible light through the near-infrared.

The technique could allow advanced thermal imaging systems to be produced more quickly and inexpensively and with higher sensitivity. It holds potential for a variety of other applications, such as masking heat signatures, and is easily scalable, can be applied to any surface geometry and costs less than current light-absorption technologies.

A scanning electron microscope image of silver nanocubes on a gold surface.
A scanning electron microscope image of silver nanocubes on a gold surface. Altering the size and number of the nanocubes tunes the material to absorb different wavelengths. Courtesy of Maiken Mikkelsen and Gleb Akselrod/Duke University.

The technique relies on plasmonics and was developed in the lab of professor Maiken H. Mikkelsen in the department of electrical and computer engineering and physics at Duke University.

To fabricate the absorbers, researchers first coated a surface with a thin film of gold. They then applied a layer of polymer a few nanometers thick, followed by a coating of silver cubes, each one about 100 nm in size. Dip-coating methods were used.

When light struck the engineered surface, a specific wavelength was trapped on the surface of the nanocubes in the form of plasmons and eventually dissipated into heat. By altering the thickness of the polymer film and the size and number of silver nanocubes, the coating could be tuned to absorb different wavelengths.

Meadowlark Optics - Building system MR 7/23

A curved object covered with the coating absorbs all red light, which leaves the object with a green tint.
A curved object covered with the coating absorbs all red light, which leaves the object with a green tint. A closer look reveals that the surface is covered with tiny 100-nm silver cubes. Courtesy of Maiken Mikkelsen and Gleb Akselrod/Duke University.

"The unique absorbing properties of the nanocubes can be predicted with straightforward formulas, making it easy to quickly determine recipes for surface coatings that provide desired spectral properties," said professor David R. Smith. "The nanocube system eliminates, or at least vastly reduces, cost and manufacturing issues, so that we can focus on impacting exciting application areas such as photovoltaics or thermal coatings."

By making the nanocubes larger to absorb wavelengths corresponding to thermal radiation, the technology could suppress or mask an object's natural thermal radiation, also known as blackbody radiation.

Coating photodetectors to absorb only specific wavelengths of IR light could enable novel and cheap cameras that could image portions of the IR spectrum. Among the researchers' next steps is to convert thermal radiation to an electrical signal.

The work was published in Advanced Materials (doi: 10.1002/adma.201503281).

Published: November 2015
Glossary
plasmonics
Plasmonics is a field of science and technology that focuses on the interaction between electromagnetic radiation and free electrons in a metal or semiconductor at the nanoscale. Specifically, plasmonics deals with the collective oscillations of these free electrons, known as surface plasmons, which can confine and manipulate light on the nanometer scale. Surface plasmons are formed when incident photons couple with the conduction electrons at the interface between a metal or semiconductor...
nano
An SI prefix meaning one billionth (10-9). Nano can also be used to indicate the study of atoms, molecules and other structures and particles on the nanometer scale. Nano-optics (also referred to as nanophotonics), for example, is the study of how light and light-matter interactions behave on the nanometer scale. See nanophotonics.
metamaterial
Metamaterials are artificial materials engineered to have properties not found in naturally occurring substances. These materials are designed to manipulate electromagnetic waves in ways that are not possible with conventional materials. Metamaterials typically consist of structures or elements that are smaller than the wavelength of the waves they interact with. Key characteristics of metamaterials include: Negative refraction index: One of the most notable features of certain...
Research & TechnologyDukeMaiken MikkelsenDavid SmithplasmonicsnanometamaterialCoatingsSensors & DetectorsTech Pulse

We use cookies to improve user experience and analyze our website traffic as stated in our Privacy Policy. By using this website, you agree to the use of cookies unless you have disabled them.