A beam of sunlight is a mixture of different-colored light, including all the colors of the rainbow. Filtering or blocking a specific color, or colors, is often important in photography, color displays and other imaging techniques.
Altering the size and separation of these nanoscale mirrors changes the color of light that they reflect.
Copyright : 2013 A*STAR Institute of Materials Research and Engineering
An international team of engineers has now fabricated arrays of silver nanoscale pillars that can selectively reflect light of any desired color1. The team, led by Jinghua Teng and Yan Jun Liu at the A*STAR Institute of Materials Research and Engineering in Singapore, show that the color can be selected by varying the size of the pillars.
The stained glass in the windows of a church owes its color in part to an effect called surface plasmon resonance: light passing through the window interacts with electrons in the nanometer-sized metallic impurities that are trapped in the glass.
Light of a specific color, or wavelength, forces these electrons to quickly oscillate. In turn, the oscillating electrons enhance the amount of light transmitted through the glass at this wavelength. Teng, Liu and their co-workers were able to transfer this plasmonic effect from light-transmitting windows to light-reflecting mirrors. “Our compact reflectors could be used for applications including color coding, anti-counterfeiting and product branding,” says Teng.
The researchers deposited 6 nanometers of titanium, followed by 180 nanometers of silver on a quartz substrate. Onto the silver layer, they etched arrays of cylinders with diameters of 300 to 500 nanometers and a center-to-center separation of 320 to 540 nanometers (see image). The resulting gap between some of the pillars was as small as 20 nanometers. To achieve these tiny features, the team used a technique called electron-beam lithography: they scanned a beam of electrons to pattern the required features onto a protective layer placed on top of the silver. Then, they used a stream of charged ion atoms to mill the exposed metal and create the nanopillars.
After construction, Teng, Liu and their team shone white light onto each of the arrays and measured the wavelength of the reflected radiation. Arrays of cylinders of 500 nanometers in diameter and separated by 40 nanometers appeared red because they predominantly reflected light with a wavelength of 630 nanometers. Similarly, pillars with a diameter of 300 nanometers and a separation of 20 nanometers appeared blue as they reflected light with a 490-nanometer wavelength.
“We are now working to further develop this technique to create large-area color displays,” says Teng. “We also aim to develop applications and collaborations with industry.”
Si, G., Zhao, Y., Lv, J., Lu, M., Wang, F. et al. Reflective plasmonic color filters based on lithographically patterned silver nanorod arrays. Nanoscale 5, 6243–6248 (2013).
First direct observation and measurement of ultra-fast moving vortices in superconductors
20.07.2017 | The Hebrew University of Jerusalem
Manipulating Electron Spins Without Loss of Information
19.07.2017 | Universität Basel
Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.
For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...
What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.
To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...
The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....
A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...
Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision
Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...
19.07.2017 | Event News
12.07.2017 | Event News
12.07.2017 | Event News
20.07.2017 | Information Technology
20.07.2017 | Materials Sciences
20.07.2017 | Physics and Astronomy