Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A Guiding Light on the Nanoscale

03.09.2004


At left a zinc-oxide nanowire laser is pumped with light, which is channeled into a tin-oxide nanoribbon at a junction between the two materials and guided through the rest of the ribbon’s length. At right is an electron microscope image of the junction between wire and ribbon.


Another important step towards realizing the promise of lightning fast photonic technology has been taken by scientists with the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California at Berkeley. Researchers have demonstrated that semiconductor nanoribbons, single crystals measuring tens of hundreds of microns in length, but only a few hundred or less nanometers in width and thickness (about one ten-millionth of an inch), can serve as "waveguides" for channeling and directing the movement of light through circuitry.

"Not only have we shown that semiconductor nanoribbons can be used as low-loss and highly flexible optical waveguides, we’ve also shown that they have the potential to be integrated within other active optical components to make photonic circuits," says Peidong Yang, a chemist with Berkeley Lab’s Materials Sciences Division and a professor with UC Berkeley’s Chemistry Department, who led this research.

The research results of Yang and his team are reported in the August 27, 2004 issue of the journal Science. Co-authoring the paper along with Yang were Matt Law, Donald Sirbuly, Justin Johnson, Josh Goldberger and Richard Saykally, all of whom are with affiliated with Berkeley Lab, UC Berkeley, or both.



In photonic technology, or photonics, the use of electrons moving through semiconductors as information carriers is replaced with the movement of light waves, as measured in units of energy called photons. Whereas electrons must carry information sequentially, one electron at a time, with photons of light there’s virtually no limit to the number of information packets that can simultaneously be transmitted. Call it unparalleled parallel processing.

Hints of the potential of photonics can be glimpsed in today’s fiber-optic communications, where a single optical fiber can carry the equivalent of 300,000 telephone calls at the same time. But the power of fully realized photonics goes far beyond this. For example, it’s been estimated that a photonic internet could transmit data at 160 gigabits per second, which is thousands of times faster than today’s typical high-speed connection. Another possibility is the optical computer, which could solve problems in seconds that would take today’s electronic computers months or even years to solve.

For the promise of photonics to be delivered, however, scientists must first find a way to manipulate and route photons with the same dexterity as they manipulate and route electrons. Whereas other research efforts have successfully experimented with the use of photonic band-gap materials to accomplish this, Yang and his colleagues have focused on the chemical synthesis of nanowires and nanoribbons — they’re like nanotubes only solid throughout rather than hollow inside — that can then be assembled into photonic circuits.

"Chemically synthesized nanowires and nanoribbons have several features that make them good photonic building blocks," says Yang. "They offer inherent one-dimensionality, a diversity of optical and electrical properties, good size control, low surface roughness and, in principle, the ability to operate above and below light-diffraction limits."

Yang and his colleagues synthesized their nanoribbon waveguides from tin oxide, a semiconductor of keen technological interest for its exceptional potential for use in transporting both photons and electrons in nanoscale (also referred to as "subwavelength") components. The single crystalline nanoribbons they produced measured about 1,500 microns in length and featured a variety of widths and thicknesses. Yang says ribbons that measured between 100 to 400 nanometers in width and thickness proved to be ideal for guiding visible and ultraviolet light.

"To steer visible and ultraviolet light within dielectric waveguides, such as the tin oxide crystals we were synthesizing, we needed to make sure that a sufficient portion of the light’s electromagnetic field was confined within the nanostructures so there would be minimal optical transmission loss," Yang says. "Considering the dielectric constant of the tin oxide, it follows that the diameter of 100 to 400 nanometers would be ideal for waveguiding light that measures from 300 to 800 nanometers in wavelengths."

In their tests, Yang and his colleagues attached nanowire lasers and optical detectors to opposite ends of their tin oxide nanoribbons, then demonstrated that light could be propagated and modulated through subwavelength optical cavities within the nanoribbons. The nanoribbons were long and strong enough to be pushed, bent, and shaped with the use of a commercial micromanipulator under an optical microscope. Freestanding ribbons were also extremely flexible and could be curved through tight S-turns and twisted into a variety of shapes, which Yang says is "remarkable for a crystal that is brittle in its bulk form."

Yang also says that while the nanoribbon waveguides can be coupled together to create optical networks that could serve as the basis of miniaturized photonic circuitry, the ribbons need to be in close proximity, preferably in direct physical contact, to enable an efficient transfer of light between them. "We tested various coupling geometries and found that a staggered side-by-side arrangement, in which two ribbons interact over a distance of several micrometers, outperforms direct end-to-end coupling," Yang says.

The nanoribbon waveguides that Yang and his co-authors report in their Science paper are the newest addition to the growing assortment of nanosized device elements that Yang and his research group have been able to make. Their "toolbox" now includes nanoscale lasers and photodetectors, in addition to the nanoribbon waveguides.

"Ultimately, we would like to integrate all these individual components together into a photonic system-on-a-chip, so that many photonic operations, including light emission, routing, and detection, can be done on a much smaller scale," says Yang.

Lynn Yarris | EurekAlert!
Further information:
http://www.lbl.gov

More articles from Power and Electrical Engineering:

nachricht A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes
20.07.2018 | Science China Press

nachricht Future electronic components to be printed like newspapers
20.07.2018 | Purdue University

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

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

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>