Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Berkeley Lab Researchers Use Metamaterials to Observe Giant Photonic Spin Hall Effect

22.03.2013
Researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) have once again demonstrated the incredible capabilities of metamaterials – artificial nanoconstructs whose optical properties arise from their physical structure rather than their chemical composition.
Engineering a unique two-dimensional sheet of gold nanoantennas, the researchers 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.

“With metamaterial, we were able to greatly enhance a naturally weak effect to the point where it was directly observable with simple detection techniques,” said Xiang Zhang, a faculty scientist with Berkeley Lab’s Materials Sciences Division who led this research. “We also demonstrated that metamaterials not only allow us to control the propagation of light but also allows control of circular polarization. This could have profound consequences for information encoding and processing.”

Zhang is the corresponding author of a paper describing this work in the journal Science. The paper is titled “Photonic Spin Hall Effect at Metasurfaces.” Co-authors are Xiaobo Yin, Ziliang Ye, Jun Sun Rho and Yuan Wang.

The spin Hall effect, named in honor of physicist Edwin Hall, describes the curved path that spinning electrons follow as they move through a semiconductor. The curved movement arises from the interaction between the physical motion of the electron and its spin – a quantized angular momentum that gives rise to magnetic moment. Think of a baseball pitcher putting spin on a ball to make it curve to the left or right.

“Light moving through a metal also displays the spin Hall effect but the photonic spin Hall effect is very weak because the spin angular momentum of photons and spin-orbit interactions are very small,” says Xiaobo Yin, a member of Zhang’s research group and the lead author of the Science paper. “In the past, people have managed to observe the photonic spin Hall effect by generating the process over and over again to obtain an accumulative signal, or by using highly sophisticated quantum measurements. Our metamaterial makes the photonic spin Hall effect observable even with a simple camera.”

Metamaterials have garnered a lot of attention in recent years because their unique structure affords electromagnetic properties unattainable in nature. For example, a metamaterial can have a negative index of refraction, the ability to bend light backwards, unlike all materials found in nature, which bend light forward. Zhang, who holds the Ernest S. Kuh Endowed Chair Professor of Mechanical Engineering at the University of California (UC) Berkeley, where he also directs the National Science Foundation’s Nano-scale Science and Engineering Center, has been at the forefront of metamaterials research. For this study, he and his group fashioned metamaterial surfaces about 30 nanometers thick (a human hair by comparison is between 50,000 and 100,000 nanometers thick). These metasurfaces were constructed from V-shaped gold nanoantennas whose geometry could be configured by adjusting the length and orientation of the arms of the Vs.

“We chose eight different antenna configurations with optimized geometry parameters to generate a linear phase gradient along the x direction,” says Yin. “This enabled us to control the propagation of the light and introduce strong photon spin-orbit interactions through rapid changes in direction. The photonic spin Hall effect depends on the curvature of the light’s trajectory, so the sharper the change in propagation direction, the stronger the effect.”
Since the entire metasurface sample measured only 0.3 millimeters, a 50-millimeter lens was used to project the transmission of the light through the metamaterial onto a charge-coupled device (CCD) camera for imaging. From the CCD images, the researchers determined that both the control of light propagation and the giant photonic spin Hall effect were the direct results of the designed meta-material. This finding opens up a wealth of possibilities for new technologies.

“The controllable spin-orbit interaction and momentum transfer between spin and orbital angular momentum allows us to manipulate the information encoded on the polarization of light, much like the 0 and 1 of today’s electronic devices,” Yin says. “But photonic devices could encode more information and provide greater information security than conventional electronic devices.”

Yin says the ability to control left and right circular polarization of light in metamaterial surfaces should allow for the formation of optical elements, like highly coveted “flat lenses,” or the management of light polarization without using wave plates.

“Metamaterials provide us with tremendous design freedom that will allow us to modulate the strength of the photonic spin Hall effect at different spatial locations,” Yin says. “We knew the photonic spin Hall effect existed in nature but it was so hard to detect. Now, with the right metamaterials we can not only enhance this effect we can harness it for our own purposes.”

This research was supported by the DOE Office of Science.

Lawrence Berkeley National Laboratory addresses the world’s most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab’s scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy’s Office of Science. For more, visit www.lbl.gov.

DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit the Office of Science website at science.energy.gov/.

Lynn Yarris | EurekAlert!
Further information:
http://www.lbl.gov
http://newscenter.lbl.gov/news-releases/2013/03/21/berkeley-lab-researchers-use-metamaterials-to-observe-giant-photonic-spin-hall-effec

More articles from Physics and Astronomy:

nachricht Observations of nearby supernova and associated jet cocoon provide new insights on gamma-ray bursts
18.01.2019 | George Washington University

nachricht A new twist on a mesmerizing story
17.01.2019 | ETH Zurich Department of Physics

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Ten-year anniversary of the Neumayer Station III

The scientific and political community alike stress the importance of German Antarctic research

Joint Press Release from the BMBF and AWI

The Antarctic is a frigid continent south of the Antarctic Circle, where researchers are the only inhabitants. Despite the hostile conditions, here the Alfred...

Im Focus: Ultra ultrasound to transform new tech

World first experiments on sensor that may revolutionise everything from medical devices to unmanned vehicles

The new sensor - capable of detecting vibrations of living cells - may revolutionise everything from medical devices to unmanned vehicles.

Im Focus: Flying Optical Cats for Quantum Communication

Dead and alive at the same time? Researchers at the Max Planck Institute of Quantum Optics have implemented Erwin Schrödinger’s paradoxical gedanken experiment employing an entangled atom-light state.

In 1935 Erwin Schrödinger formulated a thought experiment designed to capture the paradoxical nature of quantum physics. The crucial element of this gedanken...

Im Focus: Nanocellulose for novel implants: Ears from the 3D-printer

Cellulose obtained from wood has amazing material properties. Empa researchers are now equipping the biodegradable material with additional functionalities to produce implants for cartilage diseases using 3D printing.

It all starts with an ear. Empa researcher Michael Hausmann removes the object shaped like a human ear from the 3D printer and explains:

Im Focus: Elucidating the Atomic Mechanism of Superlubricity

The phenomenon of so-called superlubricity is known, but so far the explanation at the atomic level has been missing: for example, how does extremely low friction occur in bearings? Researchers from the Fraunhofer Institutes IWM and IWS jointly deciphered a universal mechanism of superlubricity for certain diamond-like carbon layers in combination with organic lubricants. Based on this knowledge, it is now possible to formulate design rules for supra lubricating layer-lubricant combinations. The results are presented in an article in Nature Communications, volume 10.

One of the most important prerequisites for sustainable and environmentally friendly mobility is minimizing friction. Research and industry have been dedicated...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Our digital society in 2040

16.01.2019 | Event News

11th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Aachen, 3-4 April 2019

14.01.2019 | Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

 
Latest News

Additive manufacturing reflects fundamental metallurgical principles to create materials

18.01.2019 | Materials Sciences

How molecules teeter in a laser field

18.01.2019 | Life Sciences

The cytoskeleton of neurons has been found to be involved in Alzheimer's disease

18.01.2019 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>