A Chinese-U.S. research team is exploring the use of metamaterials to create devices that manipulate sound in versatile and unprecedented ways. In a recently published paper, the team reports a simple design for a device, called an acoustic field rotator, which can twist wave fronts inside it so that they appear to be propagating from another direction.
Univ. of Colorado Boulder scientists have found a creative way to radically improve thermoelectric materials, a finding that could one day lead to the development of improved solar panels and more energy-efficient cooling equipment. The technique, building an array of tiny pillars on top of a sheet of thermoelectric material, represents an entirely new way of attacking a century-old problem.
Researchers in California have made progress in a project to develop fast-blinking light-emitting diode systems for underwater optical communications. They have shown that an artificial metamaterial can improve the “blink speed” of a fluorescent light-emitting dye molecule 76 times faster than normal while increasing brightness 80-fold.
Scientists at Ames Laboratory have demonstrated broadband terahertz (THz) wave generation using metamaterials. The discovery may help develop noninvasive imaging and sensing, and make possible THz-speed information communication, processing and storage.
Inventor Nikola Tesla imagined the technology to transmit energy through thin air almost a century ago, but experimental attempts at the feat have so far resulted in cumbersome devices that only work over very small distances. But now, Duke Univ. researchers have demonstrated the feasibility of wireless power transfer using low-frequency magnetic fields over distances much larger than the size of the transmitter and receiver.
The field of metamaterials has produced structures with unprecedented abilities, including flat lenses, invisibility cloaks and even optical metatronic devices that can manipulate light in the way electronic circuitry manipulates the flow of electrons. Now, the birthplace of the digital computer, ENIAC, is using this technology in the rebirth of analog computing.
Researchers at The Univ. of Texas at Austin have proposed the first design of a cloaking device that uses an external source of energy to significantly broaden its bandwidth of operation. The team has proposed a design for an active cloak that draws energy from a battery, allowing objects to become undetectable to radio sensors over a greater range of frequencies.
The Information Age will get a major upgrade with the arrival of quantum processors faster and more powerful than today’s supercomputers. For the benefits of this new Information Age 2.0 to be fully realized, however, quantum computers will need fast and efficient multi-directional light sources. While quantum technologies remain grist for science fiction, a team of researchers has taken an important step towards efficient light generation.
Researchers have created tiny holograms using a metasurface capable of the ultra-efficient control of light, representing a potential new technology for advanced sensors, high-resolution displays and information processing. The metasurface, thousands of V-shaped nanoantennas formed into an ultra-thin gold foil, could make possible optical switches small enough to be integrated into computer chips for information processing.
The phonon, like the photon or electron, is a physical particle that travels like waves, representing mechanical vibration. Phonons transmit everyday sound and heat. Recent progress in phononics by a research scientist at Georgia Institute of Technology has led to the development of new ideas and devices that are using phononic properties to control sound and heat, even to the point of freeing bustling city blocks from the noise of traffic.
Invisibility cloaking is no longer the stuff of science fiction: Two researchers at the Univ. of Toronto have demonstrated an effective invisibility cloak that is thin, scalable and adaptive to different objects. The team designed and tested a new approach to cloaking—by surrounding an object with small antennas that collectively radiate an electromagnetic field. The radiated field cancels out any waves scattering off the cloaked object.
Using inexpensive materials configured and tuned to capture microwave signals, researchers at Duke University's Pratt School of Engineering have designed a power-harvesting device with efficiency similar to that of modern solar panels. The device wirelessly converts the microwave signal to direct current voltage capable of recharging a cell phone battery or other small electronic device.
Gems are known for the beauty of the light that passes through them. But it is the fixed atomic arrangements of these crystals that determine the light frequencies permitted passage. Now a Sandia National Laboratories-led team has created a plasmonic, or plasma-containing, crystal that is tunable. The effect is achieved by adjusting a voltage applied to the plasma.
A brain stimulation technique that is used to treat tough cases of depression could be considerably improved with a new headpiece designed by Univ. of Michigan engineers. Computer simulations showed that the headpiece—a square array of 64 circular metallic coils—could one day help researchers and doctors hit finer targets in the brain that are twice as deep as they can reach today, and without causing pain.
A lens with ten times the resolution of any current lens, making it a powerful new tool for the biological sciences, has been developed by researchers at the Univ. of Sydney. The lens was created using fiber-optic manufacturing technology, and is a metamaterial, or a material with completely new properties not found in nature.
Scientists in Germany have developed a mathematical model for a type of microscopic test lab that could provide new and deeper insight into the world of quantum particles. The new test system will enable the simultaneous study of one hundred light quanta, or photons, and their quantum entanglements. This is a far greater number than was previously possible.
Researchers are working on a range of options to overcome a fundamental obstacle in commercializing plasmonic metamaterials that could bring advanced optical technologies for more powerful computers, new cancer treatments and other innovations. The materials could make it possible to harness clouds of electrons called "surface plasmons" to manipulate and control light.
In Physics World, a group of physicists describe how unique structures in the natural world are inspiring scientists to develop new types of materials with unprecedented properties. From adhesive tape inspired by the toes of geckos to a potential flaw-resistant coating of airplanes inspired by mother of pearl, the attractiveness centers on one concept—hierarchical design.
New ultrathin, planar, lightweight and broadband polarimetric photonic devices and optics could result from recent research by a team of Los Alamos National Laboratory scientists. The advances would boost security screening systems, infrared thermal cameras, energy harvesting and radar systems.
Metamaterials have already been fabricated that have a negative refractive index for electromagnetic waves, but controlling shorter light waves has proved far more difficult. Researchers have now synthesized metamaterials based on organic molecules as building blocks. This approach has several advantages over the metallic nanostructures previously used.
For the first time, scientists working NIST have demonstrated a new type of lens that bends and focuses ultraviolet light in a way that it can create ghostly, 3D images of objects that float in free space. The easy-to-build lens could lead to improved photolithography, nanoscale manipulation and manufacturing, and even high-resolution 3D imaging, as well as a number of as-yet-unimagined applications in a diverse range of fields.
In a process comparable to squeezing an elephant through a pinhole, researchers at Missouri University of Science and Technology have designed a way to engineer atoms capable of funneling light through ultrasmall channels. Their research is the latest in a series of recent findings related to how light and matter interact at the atomic scale.
Metamaterials are manufactured materials that derive their unusual properties from structure rather than only composition. In the past, to control the optics of metamaterials, researchers used complicated structures including 3D rings and spirals that are difficult to manufacture in large numbers and small sizes. Researchers at Penn State have applied nature-inspired optimization techniques based on genetic algorithms to simplify efforts to shape wavelength dispersion.
Up until now, the invisibility cloaks put forward by scientists have been fairly bulky contraptions—an obvious flaw for those interested in Harry Potter-style applications. However, researchers from the U.S. have now developed a cloak that is just micrometers thick and can hide 3D objects from microwaves in their natural environment, in all directions and from all of the observers’ positions.
Engineering a unique two-dimensional sheet of gold nanoantennas, researchers at Lawrence Berkeley National Laboratory were able to obtain the strongest signal yet of the photonic spin Hall effect, an optical phenomenon of quantum mechanics that could play a prominent role in the future of computing.