Single-electron transport in molecular transistors has been studied previously using top-down approaches, such as lithography and break junctions.
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but the drawback that it cannot easily absorb light when it is a large flat surface as used in Gap solar cells.
meaning that it emits light when electric current is run through it or when it is shot with a nondestructive laser.
Multilayer molybdenum disulfide, by contrast, is easier and less expensive to produce, but it is not normally luminescent.
when electrical current is passed through it. e were trying to make a vertically stacked light-emitting device based on monolayer Mos2,
So we followed this new lead to investigate the underlying mechanism and the potential of multilayer Mos2 in light-emitting devices.
with the goal of helping to create a new generation of light-emitting devices from two-dimensional layered materials,
New research from Rice university could make it easier for engineers to harness the power of light-capturing nanomaterials to boost the efficiency
In a study published July 13 in Nature Communications, scientists from Rice's Laboratory for Nanophotonics (LANP) describe a new method that solar-panel designers could use to incorporate light-capturing nanomaterials into future designs.
including metallic nanoparticles that convert light into plasmons, waves of electrons that flow like a fluid across the particles'surface.
"We can tune plasmonic structures to capture light across the entire solar spectrum, "Halas said."
The process is relatively faster, safer and green--devoid of any toxic substances (just graphite plus concentrated light.
#Reshaping the solar spectrum to turn light to electricity: UC Riverside researchers find a way to use the infrared region of the sun's spectrum to make solar cells more efficient A huge gain in this direction has now been made by a team of chemists at the University of California,
The cadmium selenide nanocrystals could convert visible wavelengths to ultraviolet photons, while the lead selenide nanocrystals could convert near-infrared photons to visible photons.
the researchers directed 980-nanometer infrared light at the hybrid material, which then generated upconverted orange yellow fluorescent 550-nanometer light,
almost doubling the energy of the incoming photons. The researchers were able to boost the upconversion process by up to three orders of magnitude by coating the cadmium selenide nanocrystals with organic ligands,
"This 550--nanometer light can be absorbed by any solar cell material, "Bardeen said.""The key to this research is the hybrid composite material--combining inorganic semiconductor nanoparticles with organic compounds.
Put simply, the inorganics in the composite material take light in; the organics get light out."
"The ability to move light energy from one wavelength to another, more useful region, for example, from red to blue, can impact any technology that involves photons as inputs or outputs,
and industries, including laser, solar cells, production of transistors and nanomedicine. The colloid form of these particles have very interesting properties and characteristics,
electronics and photonics after passing the required tests and obtaining mass-production of these nanoparticles.
Perry and colleagues in Georgia Tech's Center for Organic photonics and Electronics (COPE) had been working on other capacitor materials to meet these demands
The Utah engineers have developed an ultracompact beamsplitter--the smallest on record--for dividing light waves into two separate channels of information.
The device brings researchers closer to producing silicon photonic chips that compute and shuttle data with light instead of electrons.
Electrical and computer engineering associate professor Rajesh Menon and colleagues describe their invention today in the journal Nature Photonics Silicon photonics could significantly increase the power and speed of machines such as supercomputers
data center servers and the specialized computers that direct autonomous cars and drones with collision detection. Eventually, the technology could reach home computers
the photons of light must be converted to electrons before a router or computer can handle the information.
"With all light, computing can eventually be millions of times faster, "says Menon. To help do that, the U engineers created a much smaller form of a polarization beamsplitter
(which looks somewhat like a barcode) on top of a silicon chip that can split guided incoming light into its two components.
And because photonic chips shuttle photons instead of electrons, mobile devices such as smartphones or tablets built with this technology would consume less power,
The first supercomputers using silicon photonics--already under development at companies such as Intel and IBM--will use hybrid processors that remain partly electronic.
#Controlling light by pairing two exotic 2-D materials Researchers have found a way to couple the properties of different two-dimensional materials to provide an exceptional degree of control over light waves.
They say this has the potential to lead to new kinds of light detection, thermal-management systems,
Although the two materials are structurally similar both composed of hexagonal arrays of atoms that form two-dimensional sheets they each interact with light quite differently.
The hybrid material blocks light when a particular voltage is applied to the graphene while allowing a special kind of emission and propagation, called yperbolicity,
One of the consequences of this unusual behavior is that an extremely thin sheet of material can interact strongly with light,
while light interacting with hbn produces phonons. Fang and his colleagues found that when the materials are combined in a certain way,
The properties of the graphene allow precise control over light, while hbn provides very strong confinement and guidance of the light.
Combining the two makes it possible to create new etamaterialsthat marry the advantages of both,
The combined materials create a tuned system that can be adjusted to allow light only of certain specific wavelengths
comes from the ability to switch a light beam on and off at the material surface; because the material naturally works at near-infrared wavelengths, this could enable new avenues for infrared spectroscopy,
he says. t could even enable single-molecule resolution, Fang says, of biomolecules placed on the hybrid material surface.
says, his work represents significant progress on understanding tunable interactions of light in graphene-hbn.
They have developed the first light-emitting, transparent and flexible paper out of environmentally friendly materials via a simple, suction-filtration method.
#New anotechnology promises to make surface-enhanced Raman spectroscopy simpler (Nanowerk News) From airport security detecting explosives to art historians authenticating paintings,
Given that, few sensing techniques can match the buzz created by surface-enhanced Raman spectroscopy (SERS.
Described in a research paper published today in the journal Advanced Materials Interfaces("Ultrabroadband Metasurface for Efficient light Trapping and Localization:
A Universal Surface-Enhanced Raman Spectroscopy Substrate for All Excitation Wavelengths"),the photonics advancement aims to improve our ability to detect trace amounts of molecules in diseases, chemical warfare agents, fraudulent
and measure chemical and biological molecules using a broadband nanostructure that traps wide range of light,
When a powerful laser interacts chemical and biological molecules, the process can excite vibrational modes of these molecules and produce inelastic scattering, also called Raman scattering, of light.
As the beam hits these molecules, it can produce photons that have a different frequency from the laser light.
While rich in details, the signal from scattering is weak and difficult to read without a very powerful laser.
Unfortunately, traditional substrates are designed typically for only a very narrow range of wavelengths. This is problematic because different substrates are needed
if scientists want to use a different laser to test the same molecules. In turn, this requires more chemical molecules and substrates,
because it can trap a wide range of wavelengths and squeeze them into very small gaps to create a strongly enhanced light field.
Instead of needing all these different substrates to measure Raman signals excited by different wavelengths, you'll eventually need just one.
The oscillations in the intensity of photoelectron signal for emission normal to the surface show how long light is trapped in the form of excitonic polarization during the coherent nonlinear interaction with the silver surface.
Detecting excitons in metals could provide clues on how light is converted into electrical and chemical energy in solar cells and plants.
in order to develop active elements for technologies such as optical communications by controlling how light is reflected from a metal.
When light reflects from a mirror, the light shakes the metals free electrons and the resulting acceleration of electrons creates a nearly perfect replica of the incident light providing a reflection.
enabling the excitons to be captured experimentally by a newly developed multidimensional multiphoton photoemission spectroscopic technique.
This discovery sheds light on the primary excitonic response of solids which could allow quantum control of electrons in metals, semiconductors,
when irradiated with light or when irradiation was stopped, preventing highly accurate optogenetic control. Postdoctoral fellow Fuun Kawano, Associate professor Moritoshi Sato and their research group at the Graduate school of Arts
As a result, the research group succeeded in developing a small photoswitching protein controllable with a temporal resolution of seconds by irradiation with blue light.
Furthermore, the research group has demonstrated that Magnets can control the direction of cell motion (cell polarity) at will by blue light.
and they contain laser technology (developed by the University of Hertfordshire) to detect particulates from cars and lorries.
Coherent X-ray diffraction experiments, carried out at the LCLS X-ray free electron laser facility at Stanford, have allowed snapshot imaging of a single 300 nm gold nanocrystal in the picosecond time interval after the particle was excited with a laser.
The crystal was found to expand uniformly following the excitation and to reach the melting point about 50 ps later("Imaging transient melting of a nanocrystal using an X-ray laser").
"What is striking about the result, shown in the figure, is that the crystal melts from the outside
Imaging transient melting of a nanocrystal using an x-ray laser. Snapshot projection images of a gold nanocrystal, 300nm across, before and after excitation with a femtosecond laser.
The second image, 50 picoseconds after excitation, displays a low density skin that returns to the original density at later times This result has significant implications beyond our basic understanding of the melting process.
Ian Robinson, coordinator of the project said"Bragg Coherent Diffraction Imaging is an emerging X-ray technique with great potential for probing the dynamics of matter.
Students and faculty at Vanderbilt University fabricated these tiny Archimedes spirals and then used ultrafast lasers at Vanderbilt and the Pacific Northwest National Laboratory in Richland, Washington,
The results are reported in a paper published online by the Journal of Nanophotonics("Efflcient forward second-harmonic generation from planar archimedean nanospirals".
When these spirals are shrunk to sizes smaller than the wavelength of visible light, they develop unusual optical properties.
For example, when they are illuminated with infrared laser light, they emit visible blue light. A number of crystals produce this effect, called frequency doubling or harmonic generation, to various degrees.
The strongest frequency doubler previously known is the synthetic crystal beta barium borate, but the nano-spirals produce four times more blue light per unit volume.
When infrared laser light strikes the tiny spirals it is absorbed by electrons in the gold arms.
The arms are so thin that the electrons are forced to move along the spiral. Electrons that are driven toward the center absorb enough energy
so that some of them emit blue light at double the frequency of the incoming infrared light. This is similar to
The electrons at the center of the spirals are driven pretty vigorously by the lasers electric field.
The blue light is exactly an octave higher than the infrared the second harmonic. Computer simulation of the harmonic emissions produced by a nano-spiral
when it is being illuminated by infrared light. Image: Haglund Lab/Vanderbilt) The nano-spirals also have a distinctive response to polarized laser light.
Linearly polarized light, like that produced by a Polaroid filter, vibrates in a single plane.
When struck by such a light beam, the amount of blue light the nano-spirals emit varies as the angle of the plane of polarization is rotated through 360 degrees.
The effect is even more dramatic when circularly polarized laser light is used. In circularly polarized light, the polarization plane rotates either clockwise or counterclockwise.
When left-handed nano-spirals are illuminated with clockwise polarized light the amount of blue light produced is maximized
because the polarization pushes the electrons toward the center of the spiral. Counterclockwise polarized light,
on the other hand, produces a minimal amount of blue light because the polarization tends to push the electrons outward
so that the waves from all around the nano-spiral interfere destructively. The combination of the unique characteristics of their frequency doubling and response to polarized light provide the nano-spirals with a unique,
customizable signature that would be extremely difficult to counterfeit, the researchers said. So far, Davidson has experimented with small arrays of gold nano-spirals on a glass substrate made using scanning electron-beam lithography.
Silver and platinum nano-spirals could be made in the same way. Because of the tiny quantities of metal actually used, they can be made inexpensively out of precious metals,
which resist chemical degradation. They can also be made on plastic, paper and a number of other substrates.
QDS have attracted significant attention as potential components of next-generation solid-state light sources, including LEDS s
"In an article published in Scientific Reports("Direct laser-writing of ferroelectric single-crystal waveguide architectures in glass for 3d integrated optics),
"the group said it had employed ultrafast femtosecond lasers to produce a three-dimensional single crystal capable of guiding light waves through glass with little loss of light.
A polarized light field microscope image shows crystal junctions written inside glass with a femtosecond laser.
The group says its achievement will boost ongoing efforts to develop photonic integrated circuits (PICS) that are smaller, cheaper, more energy-efficient and more reliable than current networks that use discrete optoelectronic components--waveguides, splitters, modulators, filters
to prevent light from scattering as it is being transmitted and, second, to transmit and manipulate light signals fast enough to handle increasingly large quantities of data.
Glass, an amorphous material with an inherently disordered atomic structure, cannot meet these challenges, the researchers say.
therefore essential for 3d laser-fabrication of PICS to achieve its full potential.""To pattern crystals in glass, the Lehigh-led group employed femtosecond lasers,
whose speed and precision make them useful for cataract and other eye surgeries. A femtosecond is one-quadrillionth,
Pulses emitted by femtosecond lasers last between a few femtoseconds and hundreds of femtoseconds. Scientists have been attempting for years to make crystals in glass in order to prevent light from being scattered as light signals are transmitted,
says Jain. The task is complicated by the"mutually exclusive"nature of the properties of crystal and glass.
"We have made the equivalent of a wire to guide the light. With our crystal, it is possible to do this in 3d
so that the wire--the light--can curve and bend as it is transmitted. This gives us the potential of putting different components on different layers of glass."
and for steering light from one place to another as a supermarket scanner does. Ferroelectric crystals can also transform light from one frequency to another.
This makes it possible to send light through different channels.""""Other groups have made crystal in glass
but were not able to demonstrate quality, "says Jain.""With the quality of our crystal, we have crossed the threshold for the idea to be useful.
"The femtosecond laser provides several critical advantages, say Dierolf and Jain. The high intensity of the laser pulse enables nonlinear optical absorption.
The precise focus enables researchers to control where the laser is focused and where light is absorbed."
"We can heat the glass only locally, "says Jain, "creating the desired conditions and causing the glass to melt,
or almost melt, until it is transformed into a crystal.""The unique focus of the femtosecond laser also makes it possible to"write"the crystal inside the glass and not on its surface."
"We don't want to write on the surface, only deep inside the glass,"says Jain.""Somehow, you have to get the laser inside the glass before you turn it on.
We do that by exploiting a property of the femtosecond lasers--that only at the focal point of the laser is there sufficient intensity to cause the change you want."
"The nonlinear absorption of light, says Dierolf, depends on the intensity of light in selected areas."
"If you double the intensity of the laser, you might get 20 to 100 times more absorption.
You can do this with femtosecond pulses that are very intense for a very short period of time.
Kyoto has a special lab for this. We have received now a CREF Critical Research Equipment Fund grant from Lehigh to set up that kind of facility here."
Structural color occurs through the interaction of light with materials that have patterns on a tiny scale,
which reflect light to make some wavelengths brighter and others darker. The discoveries published in the journal ACS Nano("Bio-Inspired Structural Colors Produced via Self-Assembly of Synthetic Melanin Nanoparticles")reflect a milestone in biomimicry research.
But now Fraunhofer researchers have developed a laser arc method with which layers of carbon almost as hard as diamond can be applied on an industrial scale at high coating rates and with high thicknesses.
Andreas Leson and Dr. Hans-Joachim Scheibe (left to right) successfully developed a laser arc method of depositing friction-reducing, wear-resistant coatings on components.
A pulsed laser controls the light arc In a similar style to old-fashioned film projectors, the laser arc method generates an arc between an anode and a cathode (the carbon) in a vacuum.
The arc is initiated by a laser pulse on the carbon target. This produces a plasma consisting of carbon ions,
which is deposited as a coating on the workpiece in the vacuum. To run this process on an industrial scale,
a pulsed laser is scanned vertically across a rotating graphite cylinder as a means of controlling the arc.
The laser arc method can be used to deposit very thick ta-C coatings of up to 20 micrometers at high coating rates.
Leson sees this as the first major step in using the laser arc method to save resources.
Andreas Leson, Hans-Joachim Scheibe and Volker Weihnacht received the 2015 Joseph von Fraunhofer Prize for the development of the laser arc method and the application of ta-C coatings
researchers use the term"nanophotonics"-so the prefix"nano"is used not here just as a fad!
Abig cantilever cannot be made to oscillate by freely propagating light, and the effects of chemical changes to its surface on the oscillation frequency would be less noticeable.
and Tunable Microtectonic Zno-Based Sensors and Photonics")."These transparent, flexible electronics which can be worn as skin patches
These droplets are made by melting a thin metal film using a pulsed laser. Their work is published in Advanced Materials 3d printing is a rapidly advancing field,
They used laser light to melt copper and gold into micrometre-sized droplets and deposited these in a controlled manner.
In this method, a pulsed laser is focused on a thin metal film. that locally melts and deforms into a flying drop.
High energy In this study, the researchers used a surprisingly high laser energy in comparison to earlier work,
In previous attempts, physicists used low laser energies. This allowed them to print smaller drops,
They had predicted previously this speed for different laser energies and materials. This means that the results can be translated readily to other metals as well.
One remaining problem is that the high laser energy also results in droplets landing on the substrate next to the desired location.
#3d potential through laser annihilation (Nanowerk News) Whether in the pages of H g wells, the serial adventures of Flash gordon,
or that epic science fiction saga that is Star wars, the appearance of laser beamsor rays or phasers or blastersultimately meant the imminent disintegration of our hero
Phay Ho, Chris Knight and Linda Young, Argonne National Laboratory) Today we recognize the laser is reality beyond science fiction,
Yet, harnessing the once-fabled destructive capabilities of certain lasers is proving invaluable on the path toward scientific discovery.
The x-ray electron-free laser (XFEL) is the perfect example of new technology and old perceptions converging on that narrow boundary between science and science fiction.
and interpreting the diffraction patterns they create, says Linda Young, director of APSS X-ray Science Division (XSD).
Diffraction patterns are created when x-ray photons collide with the electrons of a target samplea specific atom or enzyme molecule, for instanceand scatter.
and provide an accurate interpretation of the data recorded in diffraction patterns, explains Phay Ho, an assistant physicist with APS.
All of the work with the XFEL was performed at the Linac Coherent light Source (LCLS) at Stanford universitys SLAC National Accelerator Laboratory
issue of Physical Review Letters("Strong Asymmetric Charge Carrier Dependence in Inelastic Electron Tunneling Spectroscopy of Graphene Phonons").
The technique, called inelastic electron tunneling spectroscopy, elicits only a small blip that can be hard to pick out over more raucous disturbances."
using ultraviolet light. The end result is safe drinking water that also tastes good. Earlier this year, Wrights team won a grant from the United states Agency for International Development (USAID),
and the Diamond Light source in Oxfordshire, England. In the process, they discovered why the electrons are so fast and mobile.
#Sweeping lasers snap together nanoscale geometric grids Down at the nanoscale, where objects span just billionths of a meter,
and x-ray scattering at the National Synchrotron Light Sourceoth DOE Office of Science User Facilities.
an intensely hot laser swept across the sample to transform disordered polymer blocks into precise arrangements in just seconds."
"Our laser technique forces the materials to assemble in a particular way. We can then build structures layer-by-layer,
"Laser-assembled nanowires For the first step in grid construction, the team took advantage of their recent invention of laser zone annealing (LZA) to produce the extremely localized thermal spikes needed to drive ultra-fast self-assembly.
The sweeping laser's heat causes the elastic layer to expandike shrinkwrap in reversehich pulls
"The direction of the laser sweeping across each unassembled layer determines the orientation of the nanowire rows,
"We shift that laser direction on each layer, and the way the rows intersect and overlap shapes the grid.
The new technique may also impact photonics on silicon, with active photonic components integrated seamlessly with electronics for greater functionality.
#Mirrorlike display creates rich color pixels by harnessing ambient light (Nanowerk News) Using a simple structure comprising a mirror
researchers have developed a display technology that harnesses natural ambient light to produce an unprecedented range of colors
thus coloring the reflected light. The gap is controlled to produce nearly every conceivable color, not just the red, green,
"The incredibly efficient display is able to create a rich palette of colors using only ambient light for viewing,
"Harnessing Ambient light Typical color displays are essential yet power-hungry components of virtually every digital product with a human-machine interface, from cell phones and computers to home televisions and massive displays
Since even the most energy-efficient models require some form of backlighting, they can quickly draw-down a power supply.
engineers have been exploring ways to replace emissive technologies with displays that can reflect ambient light. Earlier attempts to create reflective light color displays,
however, presented a number of vexing problems. The designs required using three separate pixels to produce the red
Though adequate for certain applications, the fact that only one-third of the incoming light can be reflected back toward the viewer in a typical reflective RGB format limits the gamut of colors and brightness of the display.
The new display reported in Optica is able to overcome these hurdles by reflecting more of the incoming light
and enabling the full spectrum of visible light to be displayed, including bright white and deep black.
Hong and his colleagues were able achieve these results by using a property of light they call interferometric absorption to create a broad spectrum of colors.
The first layer consists of a thin absorbing material that lets most of the light pass through to the second mirror layer where it is reflected back upon itself.
With this design, the incoming light and the reflected light interfere with one another, producing a variety of standing waves with each component periodicity producing a unique color in the spectrum.
lithography and etching processes that are used to create liquid crystal displays.""Our goal is to improve the technology
with only the light behind you shining on the page
#Single-nanocatalyst water splitter produces clean-burning hydrogen 24/7 (Nanowerk News) Stanford university scientists have invented a low-cost water splitter that uses a single catalyst to produce both hydrogen
By using a combination of nuclear magnetic resonance (NMR) spectroscopy and tiny scales sensitive enough to detect changes in mass of a millionth of a gram,
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