Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nanostructures taste the rainbow

29.06.2017

Combining nanophotonics and thermoelectrics, engineers at Caltech generate materials capable of distinguishing between tiny differences in wavelengths of light

Engineers at Caltech have for the first time developed a light detector that combines two disparate technologies -- nanophotonics, which manipulates light at the nanoscale, and thermoelectrics, which translates temperature differences directly into electron voltage -- to distinguish different wavelengths (colors) of light, including both visible and infrared wavelengths, at high resolution.


This is an artist's representation of a conceptual design for the color detector, which uses thermoelectric structures with arrays of nanoscale wires that absorb different wavelengths of light based on their width.

Credit: Harry Atwater and Kelly Mauser/Caltech

Light detectors that distinguish between different colors of light or heat are used in a variety of applications, including satellites that study changing vegetation and landscape on the earth and medical imagers that distinguish between healthy and cancerous cells based on their color variations.

The new detector, described in a paper in Nature Nanotechnology on May 22, operates about 10 to 100 times faster than current comparable thermoelectric devices and is capable of detecting light across a wider range of the electromagnetic spectrum than traditional light detectors.

In traditional light detectors, incoming photons of light are absorbed in a semiconductor and excite electrons that are captured by the detector. The movement of these light-excited electrons produces an electric current -- a signal -- that can be measured and quantified. While effective, this type of system makes it difficult to "see" infrared light, which is made up of lower-energy photons than those in visible light.

Because the new detectors are potentially capable of capturing infrared wavelengths of sunlight and heat that cannot be collected efficiently by conventional solar materials, the technology could lead to better solar cells and imaging devices.

"In nanophotonics, we study the way light interacts with structures that are much smaller than the optical wavelength itself, which results in extreme confinement of light. In this work, we have combined this attribute with the power conversion characteristics of thermoelectrics to enable a new type of optoelectronic device," says Harry Atwater, corresponding author of the study.

Atwater is the Howard Hughes Professor of Applied Physics and Materials Science in the Division of Engineering and Applied Science at Caltech, and director of the Joint Center for Artificial Photosynthesis (JCAP). JCAP is a Department of Energy (DOE) Energy Innovation Hub focused on developing a cost-effective method of turning sunlight, water, and carbon dioxide into fuel. It is led by Caltech with Berkeley Lab as a major partner.

Atwater's team built materials with nanostructures that are hundreds of nanometers wide -- smaller even than the wavelengths of light that represent the visible spectrum, which ranges from about 400 to 700 nanometers.

The researchers created nanostructures with a variety of widths, that absorb different wavelengths -- colors -- of light. When these nanostructures absorb light, they generate an electric current with a strength that corresponds to the light wavelength that is absorbed.

The detectors were fabricated in the Kavli Nanoscience Institute cleanroom at Caltech, where the team created subwavelength structures using a combination of vapor deposition (which condenses atom-thin layers of material on a surface from an element-rich mist) and electron beam lithography (which then cuts nanoscale patterns in that material using a focused beam of electrons).

The structures, which resonate and generate a signal when they absorb photons with specific wavelengths, were created from alloys with well-known thermoelectric properties, but the research is applicable to a wide range of materials, the authors say.

"This research is a bridge between two research fields, nanophotonics and thermoelectrics, that don't often interact, and creates an avenue for collaboration," says graduate student Kelly Mauser (MS '16), lead author of the Nature Nanotechnology study. "There is a plethora of unexplored and exciting application and research opportunities at the junction of these two fields."

###

The study is titled "Resonant thermoelectric nanophotonics." Coauthors from Caltech include Keith Schwab, professor of applied physics; Ragip Pala, senior research scientist; graduate student Dagny Fleischman; and postdoctoral researchers Seyoon Kim and Slobodan Mitrovic. This research was funded by DOE Office of Science grant DE-FG02-07ER46405.

The study can be found online at: https://www.nature.com/nnano/journal/vaop/ncurrent/full/nnano.2017.87.html

Media Contact

Robert
rperkins@caltech.edu
626-395-1862

 @caltech

http://www.caltech.edu 

Robert - rperkins@caltech.edu | EurekAlert!

More articles from Physics and Astronomy:

nachricht First evidence on the source of extragalactic particles
13.07.2018 | Technische Universität München

nachricht Simpler interferometer can fine tune even the quickest pulses of light
12.07.2018 | University of Rochester

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Research finds new molecular structures in boron-based nanoclusters

13.07.2018 | Materials Sciences

Algae Have Land Genes

13.07.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>