Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Researchers Create World's First Ideal Anti-Reflection Coating

Abstract:
A team of researchers from Rensselaer Polytechnic Institute has created the world's first material that reflects virtually no light. They describe an optical coating made from the material that enables vastly improved control over the basic properties of light. The research opens the door to much brighter LEDs, more efficient solar cells, and a new class of "smart" light sources that adjust to specific environments.

Researchers Create World's First Ideal Anti-Reflection Coating

Troy, NY | Posted on March 1st, 2007

A team of researchers from Rensselaer Polytechnic Institute has created the world's first material that reflects virtually no light. Reporting in the March issue of Nature Photonics, they describe an optical coating made from the material that enables vastly improved control over the basic properties of light. The research could open the door to much brighter LEDs, more efficient solar cells, and a new class of "smart" light sources that adjust to specific environments, among many other potential applications.

Most surfaces reflect some light — from a puddle of water all the way to a mirror. The new material has almost the same refractive index as air, making it an ideal building block for anti-reflection coatings. It sets a world record by decreasing the reflectivity compared to conventional anti-reflection coatings by an order of magnitude.

A fundamental property called the refractive index governs the amount of light a material reflects, as well as other optical properties such as diffraction, refraction, and the speed of light inside the material. "The refractive index is the most fundamental quantity in optics and photonics. It goes all the way back to Isaac Newton, who called it the ‘optical density,'" said E. Fred Schubert, the Wellfleet Senior Constellation Professor of the Future Chips Constellation at Rensselaer and senior author of the paper.

Schubert and his coworkers have created a material with a refractive index of 1.05, which is extremely close to the refractive index of air and the lowest ever reported. Window glass, for comparison, has a refractive index of about 1.45.

Incredible New Things in Optics and Photonics

Scientists have attempted for years to create materials that can eliminate unwanted reflections, which can degrade the performance of various optical components and devices. "We started thinking, there is no viable material available in the refractive index range 1.0-1.4," Schubert said. "If we had such a material, we could do incredible new things in optics and photonics."

So the team created one. Using a technique called oblique angle deposition, the researchers deposited silica nanorods at an angle of precisely 45 degrees on top of a thin film of aluminum nitride, which is a semiconducting material used in advanced light-emitting diodes (LEDs). From the side, the films look much like the cross section of a piece of lawn turf with the blades slightly flattened.

The technique allows the researchers to strongly reduce or even eliminate reflection at all wavelengths and incoming angles of light, Schubert said. Conventional anti-reflection coatings, although widely used, work only at a single wavelength and when the light source is positioned directly perpendicular to the material.

A Broad Spectrum of Applications

The new optical coating could find use in just about any application where light travels into or out of a material, such as:

-- More efficient solar cells. The new coating could increase the amount of light reaching the active region of a solar cell by several percent, which could have a major impact on its performance. "Conventional coatings are not appropriate for a broad spectral source like the sun," Schubert said. "The sun emits light in the ultraviolet, infrared, and visible spectral range. To use all the energy provided by the sun, we don't want any energy reflected by the solar cell surface."

-- Brighter LEDs. LEDs are increasingly being used in traffic signals, automotive lighting, and exit signs, because they draw far less electricity and last much longer than conventional fluorescent and incandescent bulbs. But current LEDs are not yet bright enough to replace the standard light bulb. Eliminating reflection could improve the luminance of LEDs, which could accelerate the replacement of conventional light sources by solid-state sources.

-- "Smart" lighting. Not only could improved LEDs provide significant energy savings, they also offer the potential for totally new functionalities. Schubert's new technique allows for vastly improved control of the basic properties of light, which could allow "smart" light sources to adjust to specific environments. Smart light sources offer the potential to alter human circadian rhythms to match changing work schedules, or to allow an automobile to imperceptibly communicate with the car behind it, according to Schubert.

-- Optical interconnects. For many computing applications, it would be ideal to communicate using photons, as opposed to the electrons that are found in electrical circuits. This is the basis of the burgeoning field of photonics. The new materials could help achieve greater control over light, helping to sustain the burgeoning photonics revolution, Schubert said.

-- High-reflectance mirrors. The idea of anti-reflection coatings also could be turned on its head, according to Schubert. The ability to precisely control a material's refractive index could be used to make extremely high-reflectance mirrors, which are used in many optical components including telescopes, optoelectronic devices, and sensors.

-- Black body radiation. The development could also advance fundamental science. A material that reflects no light is known as an ideal "black body." No such material has been available to scientists, until now. Researchers could use an ideal black body to shed light on quantum mechanics, the much-touted theory from physics that explains the inherent "weirdness" of the atomic realm.

Schubert and his coworkers have only made several samples of the new material to prove it can be done, but the oblique angle evaporation technique is already widely used in industry, and the design can be applied to any type of substrate — not just an expensive semiconductor such as aluminum nitride.

Schubert is featured in an interview about the research in the same issue of Nature Photonics.

Several other Rensselaer researchers also were involved with the project: Professors Shawn-Yu Lin and Jong Kyu Kim; and graduate students J.-Q. Xi, Martin F. Schubert, and Minfeng Chen.

The research is funded primarily by the National Science Foundation, with additional support from the U.S. Department of Energy, the U.S. Army Research Office, the New York State Office of Science, Technology and Academic Research (NYSTAR), Sandia National Laboratories, and the Samsung Advanced Institute of Technology in Korea. The substrates were provided by Crystal IS, a manufacturer of single-crystal aluminum nitride substrates for the production of high-power, high-temperature, and optoelectronic devices such as blue and ultraviolet lasers.

Under Schubert's leadership, the Future Chips Constellation focuses on innovations in materials and devices, in solid state and smart lighting, and applications such as sensing, communications, and biotechnology. A new concept in academia, Rensselaer constellations are led by outstanding faculty in fields of strategic importance. Each constellation is focused on a specific research area and comprises a multidisciplinary mix of senior and junior faculty and postdoctoral and graduate students.

####

About Rensselaer Polytechnic Institute
Rensselaer Polytechnic Institute, founded in 1824, is the nation’s oldest technological university. The university offers bachelor’s, master’s, and doctoral degrees in engineering, the sciences, information technology, architecture, management, and the humanities and social sciences. Institute programs serve undergraduates, graduate students, and working professionals around the world. Rensselaer faculty are known for pre-eminence in research conducted in a wide range of fields, with particular emphasis in biotechnology, nanotechnology, information technology, and the media arts and technology. The Institute is well known for its success in the transfer of technology from the laboratory to the marketplace so that new discoveries and inventions benefit human life, protect the environment, and strengthen economic development.

For more information, please click here

Contacts:
Jason Gorss
office: (518) 276-6098
mobile: (518) 495-5486

Copyright © Newswise

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

Optical computing/Photonic computing

Superheroes are real: Ultrasensitive nonlinear metamaterials for data transfer June 25th, 2016

A new trick for controlling emission direction in microlasers June 20th, 2016

A new form of hybrid photodetectors with quantum dots and graphene June 19th, 2016

New approach to microlasers: Technique for 'phase locking' arrays of tiny lasers could lead to terahertz security scanners June 17th, 2016

Sensors

Researchers discover new chemical sensing technique: Technique allows sharper detail -- and more information -- with near infrared light June 24th, 2016

Artificial synapse rivals biological ones in energy consumption June 21st, 2016

A new form of hybrid photodetectors with quantum dots and graphene June 19th, 2016

Drum beats from a one atom thick graphite membrane June 15th, 2016

Discoveries

How cancer cells spread and squeeze through tiny blood vessels (video) June 30th, 2016

Texas A&M Chemist Says Trapped Electrons To Blame For Lack Of Battery Efficiency: Forget mousetraps — today’s scientists will get the cheese if they manage to build a better battery June 28th, 2016

Building a smart cardiac patch: 'Bionic' cardiac patch could one day monitor and respond to cardiac problems June 28th, 2016

New, better way to build circuits for world's first useful quantum computers June 28th, 2016

Announcements

How cancer cells spread and squeeze through tiny blood vessels (video) June 30th, 2016

Oxford Instruments and Dresden High Magnetic Field Laboratory collaborate to develop HTS magnet technology components for high field superconducting magnet systems June 29th, 2016

Texas A&M Chemist Says Trapped Electrons To Blame For Lack Of Battery Efficiency: Forget mousetraps — today’s scientists will get the cheese if they manage to build a better battery June 28th, 2016

Building a smart cardiac patch: 'Bionic' cardiac patch could one day monitor and respond to cardiac problems June 28th, 2016

Energy

Yale researchers’ technology turns wasted heat into power June 27th, 2016

Nanoscientists develop the 'ultimate discovery tool': Rapid discovery power is similar to what gene chips offer biology June 25th, 2016

Researchers discover new chemical sensing technique: Technique allows sharper detail -- and more information -- with near infrared light June 24th, 2016

FEI and University of Liverpool Announce QEMSCAN Research Initiative: University of Liverpool will utilize FEI’s QEMSCAN technology to gain a better insight into oil and gas reserves & potentially change the approach to evaluating them June 22nd, 2016

Photonics/Optics/Lasers

Superheroes are real: Ultrasensitive nonlinear metamaterials for data transfer June 25th, 2016

Russian physicists create a high-precision 'quantum ruler': Physicists have devised a method for creating a special quantum entangled state June 25th, 2016

Marrying superconductors, lasers, and Bose-Einstein condensates: Chapman University Institute for Quantum Studies (IQS) member Yutaka Shikano, Ph.D., recently had research published in Scientific Reports June 20th, 2016

A new trick for controlling emission direction in microlasers June 20th, 2016

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







Car Brands
Buy website traffic