Ultrasonic imaging at 1,000 times times higher resolution | KurzweilAI

Ultrasonic imaging at 1,000 times times higher resolution | KurzweilAI: The researchers used a combination of subpicosecond laser pulses and unique nanostructures to produce acoustic phonons... at a frequency of 10 gigahertz (10 billion cycles per second).

By comparison, medical ultrasounds devices today typically reach a frequency of only about 20 megahertz...

“To generate 10 GHz acoustic frequencies in our plasmonic nanostructures we use a technique known as picosecond ultrasonics,” said author are Kevin O’Brien. “Sub-picosecond pulses of laser light excite plasmons which dissipate their energy as heat. The nanostructure rapidly expands and generates coherent acoustic phonons. This process transduces photons from the laser into coherent phonons.”

‘Hyperbolic metamaterials’ closer to reality | KurzweilAI

‘Hyperbolic metamaterials’ closer to reality | KurzweilAI: The hyperbolic metamaterial behaves as a metal when light is passing through it in one direction and like a dielectric in the perpendicular direction. This “extreme anisotropy” leads to “hyperbolic dispersion” of light and the ability to extract many more photons from devices than otherwise possible, resulting in high performance...

The list of possible applications for metamaterials includes a “planar hyperlens” that could make optical microscopes 10 times more powerful and able to see objects as small as DNA, advanced sensors, more efficient solar collectors, and quantum computing.

Graphene Antennas Would Enable Terabit Wireless Downloads

Graphene Antennas Would Enable Terabit Wireless Downloads: To make an antenna, the group says, graphene could be shaped into narrow strips of between 10 and 100 nanometers wide and one micrometer long, allowing it to transmit and receive at the terahertz frequency, which roughly corresponds to those size scales. Electromagnetic waves in the terahertz frequency would then interact with plasmonic waves—oscillations of electrons at the surface of the graphene strip—to send and receive information.

Cloak of invisibility: Engineers use plasmonics to create an invisible photodetector

Cloak of invisibility: Engineers use plasmonics to create an invisible photodetector: It may not be intuitive, but a coating of reflective metal can actually make something less visible, engineers at Stanford and UPenn have shown. They have created an invisible, light-detecting device that can "see without being seen."
At the heart of the device are silicon nanowires covered by a thin cap of gold...
By carefully designing their device – by tuning the geometries – the engineers have created a plasmonic cloak in which the scattered light from the metal and semiconductor cancel each other perfectly through a phenomenon known as destructive interference.
The rippling light waves in the metal and semiconductor create a separation of positive and negative charges in the materials – a dipole moment, in technical terms. The key is to create a dipole in the gold that is equal in strength but opposite in sign to the dipole in the silicon. When equally strong positive and negative dipoles meet, they cancel each other and the system becomes invisible.

DNA Origami Revolutionizes Metamaterial Manufacture - Technology Review

DNA Origami Revolutionizes Metamaterial Manufacture - Technology Review: The idea here is to cover gold nanoparticles with short strands of single strand DNA. At the same time, the complement of this strand is built into a bigger DNA structure called a scaffold. When the nanoparticles are placed in solution with the DNA scaffold, the complementary DNA strands bond together, attaching the nanoparticles to the scaffold...
Kuzyk and co have used this process to bind nine gold nanoparticles just 10nm across to strands of DNA, forming a helical shape. So the particles form the steps in a tiny spiral staircase...
The result is a fluid that takes on the optical properties of the helical nanoparticle structures. Any circularly polarised light travelling through the spiral will excite electronic waves called plasmons on the surface of the gold nanoparticles.

Bendy 'plasmon' beams focus better than light alone - physics-math - 19 August 2011 - New Scientist

Bendy 'plasmon' beams focus better than light alone: ...until now, rigid gratings have been needed to direct and steer plasmons to a given point so that they could image something there.

Peng Zhang at the University of California, Berkeley, and colleagues can now bend beams of plasmons to their whim. They sent laser light through a screen on which a pattern was displayed. This pattern split the light into beams that interfered with each other to create what appeared to be a single beam that arced through space.

Physicists Recreate 'End Of Time' in Lab - Technology Review

Physicists Recreate 'End Of Time' in Lab - Technology Review: Metamaterials can be made to behave like ordinary space with two dimensions of space and one of time. But they can also be made to behave like other types of spaces, with two dimensions of time and one of space, for example.

Smolyaninov points out that an interesting situation occurs when these two materials are place end on. If a time dimension is perpendicular to a space dimension, it simply hits a dead end. In other words, time runs out...

So what happens at the end of time? Smolyaninov says that the electromagnetic field simply diverges, which is something of an anticlimax...

Scientists engineer a surface to trap a rainbow

Scientists engineer a surface to trap a rainbow: By focusing light along this plasmonic structure, the series of grooves, or nano-gratings, slowed each wavelength of optical light. The individual colors of the visible spectrum were captured at different groove depths along the grating, resulting in a trapped rainbow of light.
Through direct optical measurements, the team showed that wavelengths of light in the 500-700nm region were “trapped” at different positions along the grating, consistent with computer simulations.

Rainbow-trapping scientist now strives to slow light waves even further

Rainbow-trapping scientist now strives to slow light waves even further: Gan and his colleagues created nanoplasmonic structures by making nanoscale grooves in metallic surfaces at different depths, which alters the materials' optical properties...
According to Gan, the optical properties of the nanoplasmonic structures allow different wavelengths of light to be trapped at different positions in the structure, potentially allowing for optical data storage and enhanced nonlinear optics...
The structures Gan developed slow light down so much that they are able to trap multiple wavelengths of light on a single chip, whereas conventional methods can only trap a single wavelength in a narrow band.

Trapping a rainbow: Researchers slow broadband light waves with nanoplasmonic structures

Trapping a rainbow: Researchers slow broadband light waves with nanoplasmonic structures: The idea that a rainbow of broadband light could be slowed down or stopped using plasmonic structures has only recently been predicted in theoretical studies of metamaterials. The Lehigh experiment employed focused ion beams to mill a series of increasingly deeper, nanosized grooves into a thin sheet of silver. By focusing light along this plasmonic structure, this series of grooves or nano-gratings slowed each wavelength of optical light, essentially capturing each individual color of the visible spectrum at different points along the grating.

Light through a blocked hole? Plasmonics is the answer - physics-math - 11 February 2011 - New Scientist

Light through a blocked hole? Plasmonics is the answer: The team was shining light down an optical fibre that tapered to a 100-nanometre-wide aperture. At first, barely any light made it through the aperture; instead, it was reflected back up the fibre. But when the researchers placed a small gold disc very close to the aperture, so that it completely eclipsed the hole without actually touching it, the light started streaming through (see graphic, right).

They suspect that plasmons from the gold disc are leaping up through the hole, grabbing the photons stuck inside the fibre and dragging them through. These photons then stream around the edges of the disc.

Photon-plasmon coupling: Dye guides light through perforated metal foil

Photon-plasmon coupling: Dye guides light through perforated metal foil: "The researchers propose that two complementary effects are at play. On one hand, the dye molecules in the holes generate a large index variation in the hole favoring the transmission near the absorption band. On the other, the dye molecule generates a kind of “mirror image” of its electric dipole in the metal’s free electron plasma, and the dipole and mirror-image dipole interact. If the molecule then absorbs light, it is not re-emitted; instead, the light energy is completely transferred to the metal surface, where it couples with surface plasmons helping the transmission process. This combination enables the light to pass efficiently to the other side of the metal foil."

New material enables 'information sorting' at the speed of light

New material enables 'information sorting' at the speed of light: "The scientists have solved this by designing a new artificial material, which allows light beams to interact efficiently and change intensity, therefore allowing information to be sorted by beams of light at very high speeds. The structure of the tailor-made material is similar to a stack of nanoscale rods, along which light can travel and, most importantly, interact."

Low-Loss Plasmonic Metamaterials | Science/AAAS

Low-Loss Plasmonic Metamaterials | Science/AAAS: Metals have traditionally been the material of choice for the building blocks, but they suffer from high resistive losses—even metals with the highest conductivities, silver and gold, exhibit excessive losses at optical frequencies that restrict the development of devices in this frequency range. The development of new materials for low-loss MM components and telecommunication devices is therefore required.

Metamaterials and plasmonics exploit another revolutionary field in photonics, whereby the features of photonics and electronics are combined by coupling the energy and momentum of a photon to a free electron gas in the form of surface plasmons. Surface plasmons propagate on the surface of the metal, and enable the routing and manipulation of light at the nanoscale (4). Plasmonic MMs face the challenge associated with overcoming the losses that dampen these sub-wavelength coupled excitations.

Laser smaller than a hair could spark a technological revolution

Laser smaller than a hair could spark a technological revolution: They used a 45 nanometer thick layer of cadmium sulfide, a compound used in solar cells and light meters. It's a photoresister, something that resists the passage of photons, but has a resistance that decreases with the amount of light it's exposed to. The cadmium sulfide was placed next to a silver surface, with a gap of 5 nanometers between them. The gap was filled with magnesium fluoride, which allows easy passage for many different wavelengths of light.

The result has been likened to a 'whispering gallery' effect. Instead of leaking here, there and everywhere, the light is passed between the surfaces of these metals and keeps itself mostly in the little gap filled with magnesium flouride. This causes less shed heat, and keeps the laser running at room temperature.

Engineers take plasmon lasers out of deep freeze

Engineers take plasmon lasers out of deep freeze: "the researchers used a total internal reflection technique to bounce surface plasmons back inside a nano-square device. The configuration was made out of a cadmium sulfide square measuring 45 nanometers thick and 1 micrometer long placed on top of a silver surface and separated by a 5 nanometer gap of magnesium fluoride.
The scientists were able to enhance by 18-fold the emission rate of light, and confine the light to a space of about 20 nanometers, or one-twentieth the size of its wavelength. By controlling the loss of radiation, it was no longer necessary to encase the device in a vacuum cooled with liquid helium. The laser functioned at room temperature."