So they set about designing a nanostructure architecture that could provide more bang for the buck. Having previously used plasmonic materials to generate color prints at the optical diffraction limit by carefully varying the nanostructure size and spacing
We decided to extend our research to prints that would exhibit different images depending on the polarization of the incident light,
size, and structure to facilitate desired interactions with light, electrical or magnetic fields, or chemical environment to provide unique functionality in a wide range of applications from energy to medicine.
Now, a team of scientists of the Laser spectroscopy Division of Prof. Theodor W. Hnsch (Director at the Max Planck Institute of Quantum Optics and Chair for Experimental Physics at the Ludwig-Maximilians-Universitt Munich) has developed a technique
and at the same time achieves an optical resolution close to the fundamental diffraction limit. The possibility to study the optical properties of individual nanoparticles
MPQ, Laser spectroscopy Division) Spectroscopic measurements on large ensembles of nanoparticles suffer from the fact that individual differences in size, shape,
This enhances the interaction between the light and the sample, and the signal becomes easily measurable,
Laser light is coupled into the resonator through this fibre. The plane mirror is moved point by point with respect to the fibre
Then, the corresponding quantities depend on the orientation of the polarization of light with respect to the symmetry axes of the particle.
from the characterization of nanomaterials and biological nanosystems to spectroscopy of quantum emitters s
#Sensors and drones: hi-tech sentinels for crops (Nanowerk News) Sensors and drones can be among the farmers'best friends,
and the College of Optics and Photonics (CREOL) has developed a technique for creating the world first full-color,
Traditional displays like those on a mobile phone require a light source, filters and a glass plates.
flexible, color-changing displays that don need a light source their skin. ll manmade displays LCD, LED,
The new method doesn need its own light source. Rather, it reflects the ambient light around it. A thin liquid crystal layer is sandwiched over a metallic nanostructure shaped like a microscopic egg carton that absorbs some light wavelengths
and reflects others. The colors reflected can be controlled by the voltage applied to the liquid crystal layer.
The interaction between liquid crystal molecules and plasmon waves on the nanostructured metallic surface played the key role in generating the polarization-independent
"Falk and colleagues in David Awschalom's IME research group invented a new technique that uses infrared light to align spins.
Instead, the research team used light to"cool"the nuclei. While nuclei do not themselves interact with light, certain imperfections,
or"color-centers,"in the Sic crystals do. The electron spins in these color centers can be cooled readily optically and aligned,
and the materials'ability to sense long wavelength infrared (LWIR) waves due to their small energy gaps. This particular electromagnetic spectral range of LWIR is important for a range of applications such as LIDAR (light radar) systems,
basically because LWIR waves are highly transparent in earth atmosphere. This wave range also has great application for the soldiers in the military who rely on infrared thermal imaging technology and for flexible night vision glasses.
because they fit into the long wavelength-infrared light range and deliver properties that any other currently existing 2d materials cannot,
#Making new materials with micro-explosions (Nanowerk News) Scientists have made exotic new materials by creating laser-induced micro-explosions in silicon,
"Experimental evidence of new tetragonal polymorphs of silicon formed through ultrafast laser-induced confined microexplosion").
or phases, in silicon and seen indications of potentially four more,"said Professor Rode, a laser physicist at the ANU Research School of Physics and Engineering (RSPE)."
Professor Jim Williams, Professor Andrei Rode and Associate professor Jodie Bradbury with the complex electron diffraction patterns.
By focusing lasers onto silicon buried under a clear layer of silicon dioxide, the group have perfected a way to reliably blast tiny cavities in the solid silicon.
Using a combination of electron diffraction patterns and structure predictions, the team discovered the new materials have crystal structures that repeat every 12,
they are guided by a deep understanding of how lasers interact with matter, "he said. Conventional methods for creating materials with high pressure use tiny diamond anvils to poke
However, the ultra-short laser micro-explosion creates pressures many times higher than the strength of diamond crystal can produce.
The movement of electrons caused by friction was able to generate enough energy to power the lights
A laser measures this deflection, and models convert the data to reveal information about the materials composition.
The findings shed new light on a key attribute of stem cells: their ability to make new specialized cells
#Better memory with faster lasers DVDS and Blu-ray disks contain so-called phase-change materials that morph from one atomic state to another after being struck with pulses of laser light, with data"recorded"in those two atomic states.
Using ultrafast laser pulses that speed up the data recording process, Caltech researchers adopted a novel technique, ultrafast electron crystallography (UEC),
By shedding light on the fundamental physical processes involved in data storage the work may lead to better, faster computer memory systems with larger storage capacity.
"When the laser light interacts with a phase-change material, its atomic structure changes from an ordered crystalline arrangement to a more disordered,
"Today, nanosecond lasersasers that pulse light at one-billionth of a secondre used to record information on DVDS and Blu-ray disks,
Thus, with a nanosecond laser,"the fastest you can record information is one information unit
people have started to use femtosecond lasers, which can potentially record one unit every one millionth of a billionth of a second.
when it is hit by a femtosecond laser pulse. In UEC, a sample of crystalline Gete is bombarded with a femtosecond laser pulse,
followed by a pulse of electrons. The laser pulse causes the atomic structure to change from the crystalline to other structures,
and then ultimately to the amorphous state. Then when the electron pulse hits the sample, its electrons scatter in a pattern that provides a picture of the sample's atomic configuration as a function of the time.
the structural shift in Gete caused by the laser pulses. However, they also saw something more:
regardless of the laser speeds used.""Even if there is a laser faster than a femtosecond laser,
there will be a limit as to how fast this transition can occur and information can be recorded, just because of the physics of these phase-change materials,
ROM storage, including CDS and DVDS, uses phase-change materials and lasers to store information. Although ROM records
#Photonic crystal fibre: a multipurpose sensor Glass fibres can do more than transport data. A special type of glass fibre can also be used as a high-precision multipurpose sensor,
as researchers at the Max Planck Institute for the Science of Light (MPL) in Erlangen have demonstrated now("Flying particle sensors in hollow-core photonic crystal fibre").
which can literally sense different physical quantities such as electric field, temperature or vibrations through the inside of this hollow-core photonic crystal fibre.
Researchers at the Max Planck Institute for the Science of Light use a microbead which flies through the hollow channel in the interior of a photonic crystal fibre to measure different physical quantities, for example the electric field along the optical fibre.
The spatial resolution here is so high that the researchers can still accurately reproduce the configuration
What is measured is how the light sent through the fibre is affected by an external factor.
so that light can no longer propagate therein, making them unsuitable to measure radioactivity. The glass fibres which we owe particular thanks to for high rates of data transmission
The difference in refractive index ensures that the light beam is reflected at the interface to the cladding.
Two laser beams manoeuvre a microbead through a hollow glass fibre In photonic crystal fibres (PCFS), which were invented around 20 years ago by Philip Russell, Director at the Max Planck Institute for the Science of Light,
the inner channel is in contrast hollow and usually filled with air. The hollow channel is surrounded by further hollow channels that run along its entire length.
The diameter of these channels is only a few times the wavelength of light, which means that the channels affect the propagation of the light.
More precisely, they trap light in the inner channel similar to the different types of glass in conventional optical fibres.
The special properties of photonic crystal fibre, however, enable several applications that are not possible with conventional optical fibres.
whether hollow-core photonic crystal fibres are suitable as sensors by initially using the fibres to measure electric fields, vibrations and temperatures.
This was achieved by sending a laser beam through the channel from each end of the fibre.
The tiny bead reflects the light like a small mirror and thereby experiences pressure from both sides
which is generated by the impacts of the light on the particle. By setting the power of the two laser beams to different strengths,
the bead was pushed in one direction slightly more than in the other and moved through the fibre at a specific speed.
and thus reflects more laser light to the side than in the normal position. This light attenuation is measured by a photodiode at one end of the fibre.
The loss here is proportional to the strength of the electric field, and it is thus possible to determine the field from a distance.
the physicists illuminate the bead with an additional, weak laser. They use the Doppler effect here,
Wavelengths of the light behave in a similar way to the wavelength of the sound waves when emitted by moving objects.
which re-emit the radioactive radiation absorbed in the form of visible light. Information on the strength of the radioactivity at the location of the bead would then be provided by the changes in the intensity of the fluorescence.
as the laser light experiences losses as it is transmitted in the PCF, and thus the glass bead can no longer be trapped above a certain length.
and does not alter the brightness of light around a hidden object. The technology behind this cloak will have more applications than invisibility,
The idea behind cloaking is to change the scattering of electromagnetic waves--such as light and radar--off an object to make it less detectable to these wave frequencies.
It won't lose any intensity of the light that it reflects.""Many cloaks are lossy
and surface--appear flat by mimicking the reflection of light off the flat surface. Any object reflects light differently from a flat surface,
light from different points is reflected out of sync, effectively cancelling the overall distortion of light caused by the object's shape."
"This cloaking device basically fools the observer into thinking that there's a flat surface, "said Kant.
we were able to control the reflection of light at each point on the cloak,
They showed how a single nanoresonator can manipulate light to cast a very large"reflection."
"Making an object look 10,000 times larger than its physical size has lots of implications in technologies related to light,
Much like sound, light can resonate, amplifying itself as the surrounding environment manipulates the physical properties of its wave energy.
which the wavelength of light is much larger than in a vacuum, which allows light waves to resonate more powerfully.
The device condenses light to a size smaller than its wavelength meaning it can gather a lot of light energy,
and then scatters the light over a very large area, harnessing its output for imaging applications that make microscopic particles appear huge."
"We are developing photodetectors based on this technology and, for example, it could be helpful for photographers wanting to shoot better quality pictures in weak light conditions,
In addition, Yu envisions simply letting the resonator emit that energy in the form of infrared light toward the sky,
"This research opens up a new way to manipulate the flow of light, and could enable new technologies in light sensing and solar energy conversion,
"Microcavity To produce the room-temperature condensate, the team of researchers from Polytechnique and Imperial College first created a device that makes it possible for polaritons-hybrid quasiparticles that are part light
The condensate is created by first exciting a sufficient number of polaritons using a laser and then observed via the blue light it emits.
Its dimensions can be comparable to that of a human hair, a gigantic size on the quantum scale.
but also wavelike behaviour with a wavelength inversely proportional to the object's velocity. Normally, this behaviour can only be observed at atomic length scales.
the team of researchers from Polytechnique and Imperial College first created a device that makes it possible for polaritons-hybrid quasiparticles that are part light
The condensate is created by first exciting a sufficient number of polaritons using a laser and then observed via the blue light it emits.
Its dimensions can be comparable to that of a human hair, a gigantic size on the quantum scale."
Toward future polariton lasers and optical transistors In a condensate, the polaritons all behave the same way, like photons in a laser.
The study of room-temperature condensates paves the way for future technological breakthroughs such as polariton micro-lasers using low-cost organic materials,
and require less activation power than conventional lasers. Powerful transistors entirely powered by light are another possible application.
The research team foresees that the next major challenge in developing such applications will be to obtain a lower particle-condensation threshold
so that the external laser used for pumping could be replaced by more practical electrical pumping. Fertile ground for studying fundamental questions According to Professor Maier, this research is also creating a platform to facilitate the study of fundamental questions in quantum mechanics."
While Day and Mankins study focused on the wires ability to absorb different wavelengths of light,
because they are sub-wavelength in size, absorb light very efficiently, Day explained. They act almost like optical antennas,
and funnel the light into them. Previous research has shown that different diameter wires absorb different wavelengths of light.
For example, very small diameters absorb blue light well, and larger diameters absorb green light. What we showed is
if you have this modulation along the structure we can have the best of both worlds and absorb both wavelengths on the same structure.
The new wires unusual light absorption abilities dont end there, though. By shrinking the space between the crystalline structures
Day and Mankin discovered that the wires not only absorb light at specific wavelengths, they also absorb light from other parts of the spectrum.
Its actually more than a simple additive effect, Day said. As you shrink the spacing down to distances smaller than about 400 nanometers,
it creates what are called grating modes, and we see these huge absorption peaks in the infrared.
What that means is that you could absorb the same amount of infrared light with these nanowires as you could with traditional silicon materials that are 100 times thicker.
This is a powerful discovery because previously if you wanted to use nanowires for photo-detection of green and blue light, youd need two wires,
Mankin said. Now we can shrink the amount of space a device might take up by having multiple functions in a single wire.
#Degrading BPA with visible light and a new hybrid nanoparticle photocatalyst Over the course of the last half century, BPA has gone from miracle to menace.
researchers have developed a new hybrid photocatalyst that can break down BPA using visible light. Their findings, published this week in the journal APL Materials("Reduced graphene oxide and Ag wrapped Tio2 photocatalyst for enhanced visible light photocatalysis),
"from AIP Publishing, could eventually be used to treat water supplies and to more safely dispose of BPA
The photocatalytic nanomaterial can be used to treat water using visible light. How the New Catalyst Works Their new material breaks down BPA through photocatalytic oxidation, a process in
which light activates an oxidizing chemical reaction. When light strikes a photocatalyst like titanium dioxide (Tio2) nanoparticles
it takes a great deal of energy to excite electrons from one level to another--and only displays photocatalytic properties under ultraviolet light.
The addition of silver also shifted the wavelength at which the photocatalyst became excited by inducing localized surface plasmon resonance effects--a phenomenon in
and enhance light absorption over a narrow range of wavelengths. In this case, the silver shifted the wavelength of light necessary to activate the photocatalyst towards the visible light spectrum."
"The inclusion of a noble metal like silver in the ultraviolet-responsive Tio2 has extended significantly the spectrum towards the visible light through localized surface plasmon resonance effects,
"said Pichiah Saravanan, a researcher from University of Malaya who lead the project. Then, they wrapped the Ag/Tio2 nanoparticles in sheets of reduced graphene oxide (RGO), a thin layer of carbon atoms arranged in a honeycomb pattern.
When the researchers mixed the hybrid nanoparticles with BPA solution under an artificial visible light source
suggesting that both modifications played a role in the enhanced catalytic activity under visible light. Eventually, the team hopes to use their findings to help break down BPA and other contaminants in water supplies."
and ultraviolet (UV LIGHT to quickly isolate and extract a variety of contaminants from soil and water.
Nanoparticles that lose their stability upon irradiation with light have been designed to extract endocrine disruptors, pesticides,
Brandl had synthesized previously polymers that could be cleaved apart by exposure to UV LIGHT. But he and Bertrand came to question their suitability for drug delivery,
since UV LIGHT can be damaging to tissue and cells, and doesn penetrate through the skin.
When they learned that UV LIGHT was used to disinfect water in certain treatment plants, they began to ask a different question. e thought
if they are already using UV LIGHT, maybe they could use our particles as well, Brandl says. hen we came up with the idea to use our particles to remove toxic chemicals, pollutants,
because we saw that the particles aggregate once you irradiate them with UV LIGHT. A trap for ater-fearingpollution The researchers synthesized polymers from polyethylene glycol,
But when exposed to UV LIGHT, the stabilizing outer shell of the particles is shed, and now nrichedby the pollutants they form larger aggregates that can then be removed through filtration, sedimentation,
By irradiating the affected area with a pinpoint light beam, ultrasonic waves, and thermal neutrons, which can be administered safely to living organisms,
and could form the basis of optical computing. At its most basic level, your smart phone's battery is powering billions of transistors using electrons to flip on and off billions of times per second.
But first engineers must build a light source that can be turned on and off that rapidly.
While lasers can fit this requirement they are too energy-hungry and unwieldy to integrate into computer chips.
Duke university researchers are now one step closer to such a light source. In a new study, a team from the Pratt School of engineering pushed semiconductor quantum dots to emit light at more than 90 billion gigahertz.
This so-called plasmonic device could one day be used in optical computing chips or for optical communication between traditional electronic microchips.
When a laser shines on the surface of a silver cube just 75 nanometers wide,
These oscillations create their own light, which reacts again with the free electrons. Energy trapped on the surface of the nanocube in this fashion is called a plasmon.
"There is great interest in replacing lasers with LEDS for short-distance optical communication, but these ideas have always been limited by the slow emission rate of fluorescent materials,
"The heating or cooling could be done locally with lasers, tiny heaters, or thermoelectric devices placed at specific locations in the microfluidic devices.
including the changing ph of the liquid, exposure to electromagnetic radiation, or the induction of mechanical stress-all of which can change the properties of a particular hydrogel designed to be responsive to those triggers."
Today, huge amounts of data are sent incredibly fast through fibre optic-cables cables as light pulses. For that purpose they first have to be converted from electrical signals,
In Bell's days it was a simple, very thin mirror that turned sound waves into modulated light.
In a seminal paper in the scientific journal Nature Photonics("All-plasmonic Mach-Zehnder modulator enabling optical high-speed communication at the microscale"),Juerg Leuthold, professor of photonics and communications
In order to build the smallest possible modulator they first need to focus a light beam whose intensity they want to modulate into a very small volume.
however, dictate that such a volume cannot be smaller than the wavelength of the light itself.
Modern telecommunications use laser light with a wavelength of one and a half micrometers, which accordingly is the lower limit for the size of a modulator.
the light is turned first into so-called surface-plasmon-polaritons. Plasmon-polaritons are a combination of electromagnetic fields
The advantage of this detour is that plasmon-polaritons can be confined in a much smaller space than the light they originated from.
Refractive index changed from the outside In order to control the power of the light that exits the device,
For instance, a laser beam can be split onto two arms by a beam-splitter and recombined with beam combiner.
After that, the plasmons are reconverted into light, which is fed into a fibre optic cable for further transmission.
In optical communications, laser pulses are used to transmit information along fiber-optic cables for telephone service, the Internet and cable television.
or change how much light is reflected by 40 percent while requiring less power than other"all-optical"semiconductor devices. plasmonic oxide material This rendering depicts a new"plasmonic oxide material"that could make possible devices for optical communications that are at least 10 times faster than conventional
"Being able to modulate the amount of light reflected is necessary for potential industrial applications such as data transmission."
and Vladimir M. Shalaev, scientific director of nanophotonics at Purdue's Birck Nanotechnology Center and a distinguished professor of electrical and computer engineering."
"Findings were detailed in a research paper appearing in July in the journal Optica("Epsilon-near-zero Al-doped Zno for ultrafast switching at telecom wavelengths"),published by the Optical
An optical transistor could perform a similar role for light instead of electricity, bringing far faster systems than now possible.
Exposing the material to a pulsing laser light causes electrons to move from one energy level called the valence band to a higher energy level called the conduction band.
The switching speed of transistors is limited by how fast it takes conventional semiconductors such as silicon to complete this cycle of light to be absorbed,
patterns or elements that enable unprecedented control of light by harnessing clouds of electrons called surface plasmons.
which describes how much light will bend in that particular material and defines how much the speed of light slows down while passing through a material.
The pulsing laser light changes the AZO's index of refraction, which, in turn, modulates the amount of reflection
Doping the zinc oxide causes it to behave like a metal at certain wavelengths and like a dielectric at other wavelengths.
called ambient pressure X-ray photoelectron spectroscopy, revealed that the reactivity with water is key to the whole process,
#Light switches on a DVD There could be more to DVDS than has been assumed to date. The material comprised of germanium, antimony and tellurium in
which data media store information may also be suitable as an extremely fast light switch for optical communication or data processing.
"The storage mechanism in DVDS is based on the fact that laser pulses rearrange the structure of the material,
It is possible to distinguish clearly between the diffraction image of the crystal (left) and that of the amorphous material (right.
laser pulses can convert it very quickly from a strongly reflective crystalline state into a much less reflective disordered version..
Crystalline GST reflects visible light. When it is hit by a pulse of infrared light, the optical properties change in less than 100 femtoseconds one femtosecond corresponds to a millionth part of a billionth of a second.
The material then reflects 10 percent less light, while its transparency increases by 40 percent.
As the images of the electron diffraction (grey rings) show, the crystalline structure is maintained here.
The crystal lattice needs just over five picoseconds to heat up so much that it melts. In this amorphous state, the material allows 70 percent of a light beam to pass.
If it were possible to extract the energy of the infrared laser pulse before the crystal has melted
the optical properties could be changed without the material assuming a different structure. click on image to enlarge)
This is precisely what the researchers do with a short, intense laser pulse, with the direct consequence that the material no longer absorbs light as well,
and thus in the optical properties by firing a second, also very short pulse onto a thin sample of GST after the first laser pulse.
Since they varied the interval between the two light pulses in the process they were able to,
Since the researchers also sent the electrons after the exciting laser pulse with a different delay
According to the observations, more than five picoseconds this is a few millionths of a millionth of a second elapse after the exciting light pulse arrives before the crystal starts to melt.
In this way, he and his colleagues want to bring GST into a position where it can act as a light switch for optical data processing as well e
reportedly harvests the electromagnetic radiation transferring to and from mobile phones and converts it into direct current (DC) electrical energy,
Recent studies have cast a much brighter light on this underrated and extremely necessary vitamin.
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