Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Nano antenna concentrates light: Intensity increases 1,000-fold in Rice lab's experiment

Abstract:
Everybody who's ever used a TV, radio or cell phone knows what an antenna does: It captures the aerial signals that make those devices practical. A lab at Rice University has built an antenna that captures light in the same way, at a small scale that has big potential.

Nano antenna concentrates light: Intensity increases 1,000-fold in Rice lab's experiment

Houston, TX | Posted on September 23rd, 2010

Condensed matter physicist Doug Natelson and graduate student Dan Ward have found a way to make an optical antenna from two gold tips separated by a nanoscale gap that gathers light from a laser. The tips "grab the light and concentrate it down into a tiny space," Natelson said, leading to a thousand-fold increase in light intensity in the gap.

Getting an accurate measurement of the effect is a first, said Natelson, who reported the results in today's online edition of the journal Nature Nanotechnology. He expects the discovery will be useful in the development of tools for optics and for chemical and biological sensing, even at the single-molecule scale, with implications for industrial safety, defense and homeland security.

The paper by Natelson, Ward and their colleagues in Germany and Spain details the team's technique, which involves shining laser light into the gap between a pair of gold tips less than a nanometer apart - about a hundred-thousandth the width of a human hair.

"You can ignore the fact that your car antenna is built out of atoms; it just works," said Natelson, a Rice professor of physics and astronomy, and also electrical and computer engineering. "But when you have tiny pieces of metal very close to each other, you have to worry about all the details. The fields are going to be big, the situation's going to be complicated and you're really constrained. We've been able to use some physics that only come into play when things are very close together to help figure out what's going on."

The key to measuring light amplification turned out to be measuring something else, specifically the electrical current flowing between the gold tips.

Putting the nanotips so close together allows charge to flow via quantum tunneling as the electrons are pushed from one side to the other. The researchers could get electrons moving by pushing them at low frequencies with a voltage, in a highly controllable, measurable way. They could also get them flowing by shining the laser, which pushes the charge at the very high frequency of the light. Being able to compare the two processes set a standard by which the light amplification could be determined, Natelson said. Their German and Spanish coauthors helped supply the necessary theoretical justification for the analysis.

The amplification is a plasmonic effect, Natelson said. Plasmons, which may be excited by light, are oscillating electrons in metallic structures that act like ripples in a pool. "You've got a metal structure, you shine light on it, the light makes the electrons in this metal structure slosh around," he said. "You can think of the electrons in the metal as an incompressible fluid, like water in a bathtub. And when you get them sloshing back and forth, you get electric fields.

"At the surfaces of the metal, these fields can be very big - much bigger than those from the original radiation," he said. "What was hard to measure was just how big. We didn't know how much the two sides were sloshing up and down - and that's exactly the thing we care about."

By simultaneously measuring the low-frequency electrically driven and the high-frequency optically driven currents between the tips, "we can figure out the voltage zinging back and forth at the really high frequencies that are characteristic of light," he said.

Natelson said his lab's homebuilt apparatus, which combines nanoscale electronics and optics, is fairly unusual. "There are a lot of people who do optics. There are a lot who do nanoscale electrical measurements," he said. "There are still not too many people who combine the two."

The custom rig gave the Rice researchers a measure of control over thermal and electrical properties that have stymied other investigators. The tips are cooled to 80 Kelvin, about -315 degrees Fahrenheit, and are electrically insulated from their silicon bases, keeping at bay stray voltages that could skew the results.

"The reason we're studying these enhanced fields is not just because they're there," Natelson said. "If you can enhance the local field by a factor of 1,000, there are lots of things you can do in terms of sensors and non-linear optics. Anything that gives you a handle on what's happening at these tiny scales is very useful.

"This is one of those rare, happy cases where you are able to actually get information - very local information - about exactly something you care about."

The paper's co-authors are Falco Hüser and Fabian Pauly of the Karlsruhe Institute of Technology, Germany; and Juan Carlos Cuevas at the Autonomous University of Madrid, Spain.

Support for the project came from the Robert A. Welch Foundation, the Lockheed Martin Advanced Nanotechnology Center of Excellence at Rice (LANCER), Deutsche Forschungsgemeinschaft, the Baden-Württemberg Siftung, the European Union through the Bio-Inspired Approaches for Molecular Electronics (BIMORE) network, and the Spanish Ministry of Science and Innovation.

Read the abstract at www.nature.com/nnano/journal/vaop/ncurrent/abs/nnano.2010.176.html.

####

About Rice University
Located in Houston, Rice University is consistently ranked one of America's best teaching and research universities. Known for its "unconventional wisdom," Rice is distinguished by its: size -- 3,279 undergraduates and 2,277 graduate students; selectivity -- 12 applicants for each place in the freshman class; resources -- an undergraduate student-to-faculty ratio of 5-to-1; sixth largest endowment per student among American private research universities; residential college system, which builds communities that are both close-knit and diverse; and collaborative culture, which crosses disciplines, integrates teaching and research, and intermingles undergraduate and graduate work.

For more information, please click here

Contacts:
Mike Williams
713-348-6728

Copyright © Rice University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

JPK reports on the use of a NanoWizard AFM system at the University of Kaiserslautern to study the interaction of bacteria with microstructured surfaces April 28th, 2016

University of Illinois researchers create 1-step graphene patterning method April 27th, 2016

Nanograft seeded with 3 cell types promotes blood vessel formation to speed wound healing April 27th, 2016

NREL finds nanotube semiconductors well-suited for PV systems April 27th, 2016

Display technology/LEDs/SS Lighting/OLEDs

Manipulating light inside opaque layers April 24th, 2016

Highlights from the Graphene Flagship April 22nd, 2016

What screens are made of: New twists (and bends) in LCD research: X-ray research at Berkeley Lab details exotic structure formed by liquid crystals April 19th, 2016

A new way to get electricity from magnetism: 'Inverse spin Hall effect' works in several organic semiconductors April 19th, 2016

Nanoelectronics

Physicists build 'electronic synapses' for neural networks April 21st, 2016

With simple process, UW-Madison engineers fabricate fastest flexible silicon transistor April 21st, 2016

All powered up: UCI chemists create battery technology with off-the-charts charging capacity April 21st, 2016

Nature Photonics: Light source for quicker computer chips: Waveguide with integrated carbon nanotubes for conversion of electric signals into light / quicker computer chips are feasible / publication in Nature Photonics April 21st, 2016

Discoveries

Nanograft seeded with 3 cell types promotes blood vessel formation to speed wound healing April 27th, 2016

NREL finds nanotube semiconductors well-suited for PV systems April 27th, 2016

Danish researchers behind vaccine breakthrough April 27th, 2016

NREL theory establishes a path to high-performance 2-D semiconductor devices April 27th, 2016

Announcements

JPK reports on the use of a NanoWizard AFM system at the University of Kaiserslautern to study the interaction of bacteria with microstructured surfaces April 28th, 2016

University of Illinois researchers create 1-step graphene patterning method April 27th, 2016

Researchers create artificial protein to control assembly of buckyballs April 27th, 2016

Chemists use DNA to build the world's tiniest thermometer April 27th, 2016

Photonics/Optics/Lasers

NREL theory establishes a path to high-performance 2-D semiconductor devices April 27th, 2016

Physicists detect the enigmatic spin momentum of light April 26th, 2016

Rare Earth atoms see the light: Physicist Dirk Bouwmeester discovers a promising route for combined optical and solid state-based quantum information processing April 25th, 2016

Manipulating light inside opaque layers April 24th, 2016

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







Car Brands
Buy website traffic