Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Applied physicists create building blocks for a new class of optical circuits

Schematics of two types of optical circuits: the three particle trimer functions as a nanoscale magnet, while the seven particle heptamer exhibits almost no scattering for a narrow range of wavelengths due to interference. Credit: The laboratory of Federico Cappaso, Harvard School of Engineering and Applied Sciences
Schematics of two types of optical circuits: the three particle trimer functions as a nanoscale magnet, while the seven particle heptamer exhibits almost no scattering for a narrow range of wavelengths due to interference. Credit: The laboratory of Federico Cappaso, Harvard School of Engineering and Applied Sciences

Abstract:
Scalable devices inspired by nature exhibit customizable optical properties suitable for applications ranging from highly sensitive sensors and detectors to invisibility cloaks

Applied physicists create building blocks for a new class of optical circuits

Cambridge, MA | Posted on June 2nd, 2010

Imagine creating novel devices with amazing and exotic optical properties not found in nature—by simply evaporating a droplet of particles on a surface.

By chemically building clusters of nanospheres from a liquid, a team of Harvard researchers, in collaboration with scientists at Rice University, the University of Texas at Austin, and the University of Houston, has developed just that.

The finding, published in the May 28 issue of Science, demonstrates simple scalable devices that exhibit customizable optical properties suitable for applications ranging from highly sensitive sensors and detectors to invisibility cloaks. Using particles consisting of concentric metallic and insulating shells, Jonathan Fan, a graduate student at the Harvard School of Engineering and Applied Sciences (SEAS), his lead co-author Federico Capasso, Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering at SEAS, and Vinothan Manoharan, Associate professor of Chemical Engineering and Physics at SEAS and Harvard's Physics Department, devised a bottom-up, self-assembly approach to meet the design challenge.

"A longstanding challenge in optical engineering has been to find ways to make structures of size much smaller than the wavelength that exhibit desired and interesting properties," says Fan. "At visible frequencies, these structures must be nanoscale."

In contrast, most nanoscale devices are fabricated using top-down approaches, akin to how computer chips are manufactured. The smallest sizes that can be realized by such techniques are severely constrained by the intrinsic limits of the fabrication process, such as the wavelength of light used in the process. Moreover, such methods are restricted to planar geometries, are expensive, and require intense infrastructure such as cleanrooms.

"With our bottom-up approach, we mimic the way nature creates innovative structures, which exhibit extremely useful properties," explains Capasso. "Our nanoclusters behave as tiny optical circuits and could be the basis of new technology such as detectors of single molecules, efficient and biologically compatible probes in cancer therapeutics, and optical tweezers to manipulate and sort out nano-sized particles. Moreover, the fabrication process is much simpler and cheaper to carry out."

The researcher's self-assembly method requires nothing more than a bit of mixing and drying. To form the clusters, the particles are first coated with a polymer, and a droplet of them is then evaporated on a water-repellent surface. In the process of evaporation, the particles pack together into small clusters. Using polymer spacers to separate the nanoparticles, the researchers were able to controllably achieve a two nanometer gap between the particles—far better resolution than traditional top-down methods allow.

Two types of resulting optical circuits are of considerable interest. A trimer, comprising three equally-spaced particles, can support a magnetic response, an essential property of invisibility cloaks and materials that exhibit negative refractive index.

"In essence, the trimer acts as a nanoscale resonator that can support a circulating loop of current at visible and near-infrared frequencies," says Fan. "This structure functions as a nanoscale magnet at optical frequencies, something that natural materials cannot do."

Heptamers, or packed seven particle structures, exhibit almost no scattering for a narrow range of well-defined colors or wavelengths when illuminated with white light. These sharp dips, known as Fano resonances, arise from the interference of two modes of electron oscillations, a "bright" mode and a non-optically active "dark" mode, in the nanoparticle.

"Heptamers are very efficient at creating extremely intense electric fields localized in nanometer-size regions where molecules and nanoscale particles can be trapped, manipulated, and detected. Molecular sensing would rely on detecting shifts in the narrow spectra dips," says Capasso.

Ultimately, all of the self-assembled circuit designs can be readily tuned by varying the geometry, how the particles are separated, and the chemical environment. In short, the new method allows a "tool kit" for manipulating "artificial molecules" in such a way to create optical properties at will, a feature the researchers expect is broadly generalizable to a host of other characteristics.

Looking ahead, the researchers plan to work on achieving higher cluster yields and hope to assemble three-dimensional structures at the macroscale, a "holy grail" of materials science.

"We are excited by the potentially scalability of the method," says Manoharan. "Spheres are the easiest shapes to assemble as they can be readily packed together. While we only demonstrated here planar particle clusters, our method can be extended to three-dimensional structures, something that a top-down approach would have difficulty doing."

Fan, Capasso, and Manoharan's co-authors included Chihhui Wu and Gennady Shvets of University of Texas at Austin; Jiming Bao of the University of Houston; and Kui Bao, Rizia Bardhan, Naomi Halas, and Peter Norlander, all of Rice University.

The researchers acknowledge the support of National Science Foundation, the Air Force Office of Scientific Research; the U.S. Department of Defense; the Robert A. Welch Foundation; and the Center for Advanced Solar Photophysics, a U.S. Department of Energy Frontier Research Center. The work was carried out at the Center for Nanoscale Systems at Harvard, a member of the National Nanotechnology Infrastructure Network.

####

For more information, please click here

Contacts:
Michael Patrick Rutter

617-496-3815

Copyright © Harvard 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

Bosch announces high-performance MEMS acceleration sensors for wearables June 27th, 2017

Nanometrics to Participate in the 9th Annual CEO Investor Summit 2017: Accredited investor and publishing research analyst event held concurrently with SEMICON West and Intersolar 2017 in San Francisco June 27th, 2017

NMRC, University of Nottingham chooses the Quorum Q150 coater for its reliable and reproducible film thickness when coating samples with iridium June 27th, 2017

Picosun’s ALD solutions enable novel high-speed memories June 27th, 2017

Govt.-Legislation/Regulation/Funding/Policy

Atomic imperfections move quantum communication network closer to reality June 25th, 2017

Research accelerates quest for quicker, longer-lasting electronics: UC Riverside-led research makes topological insulators magnetic well above room temperatures June 25th, 2017

U.S. Air Force Research Lab Taps IBM to Build Brain-Inspired AI Supercomputing System: Equal to 64 million neurons, new neurosynaptic supercomputing system will power complex AI tasks at unprecedented speed and energy efficiency June 23rd, 2017

Rice U. chemists create 3-D printed graphene foam June 22nd, 2017

Possible Futures

Physicists make quantum leap in understanding life's nanoscale machinery June 27th, 2017

Atomic imperfections move quantum communication network closer to reality June 25th, 2017

Research accelerates quest for quicker, longer-lasting electronics: UC Riverside-led research makes topological insulators magnetic well above room temperatures June 25th, 2017

U.S. Air Force Research Lab Taps IBM to Build Brain-Inspired AI Supercomputing System: Equal to 64 million neurons, new neurosynaptic supercomputing system will power complex AI tasks at unprecedented speed and energy efficiency June 23rd, 2017

Academic/Education

Oxford Instruments congratulates Lancaster University for inaugurating the IsoLab, built for studying quantum systems June 20th, 2017

The 2017 Winners for Generation Nano June 8th, 2017

MIT Energy Initiative awards 10 seed fund grants for early-stage energy research May 4th, 2017

Bar-Ilan University to set up quantum research center May 1st, 2017

Self Assembly

Oddball enzyme provides easy path to synthetic biomaterials May 17th, 2017

Nanotubes that build themselves April 14th, 2017

Nanocages for gold particles: what is happening inside? March 16th, 2017

Most Complex Nanoparticle Crystal Ever Made by Design: Possible applications include controlling light, capturing pollutants, delivering therapeutics March 2nd, 2017

Nanomedicine

Physicists make quantum leap in understanding life's nanoscale machinery June 27th, 2017

Researchers developed nanoparticle based contrast agent for dual modal imaging of cancer June 21st, 2017

Learning with light: New system allows optical “deep learning”: Neural networks could be implemented more quickly using new photonic technology June 12th, 2017

Mussels add muscle to biocompatible fibers: Rice University chemists develop hydrogel strings using compound found in sea creatures June 9th, 2017

Sensors

Bosch announces high-performance MEMS acceleration sensors for wearables June 27th, 2017

Leti’s Autonomous-Vehicle System Embedded in Infineon’s AURIX Platform: Leti’s Low-Power, Multi-Sensor System that Transforms Distance Data into Clear Information About the Driving Environment Will Be Demonstrated at ITS Meeting in Strasbourg, June 19-22 June 20th, 2017

New diode features optically controlled capacitance: Israeli researchers have developed a new optically tunable capacitor with embedded metal nanoparticles, creating a metal-insulator-semiconductor diode that is tunable by illumination. June 8th, 2017

Graphene and quantum dots put in motion a CMOS-integrated camera that can see the invisible May 29th, 2017

Announcements

Bosch announces high-performance MEMS acceleration sensors for wearables June 27th, 2017

Nanometrics to Participate in the 9th Annual CEO Investor Summit 2017: Accredited investor and publishing research analyst event held concurrently with SEMICON West and Intersolar 2017 in San Francisco June 27th, 2017

NMRC, University of Nottingham chooses the Quorum Q150 coater for its reliable and reproducible film thickness when coating samples with iridium June 27th, 2017

Picosun’s ALD solutions enable novel high-speed memories June 27th, 2017

Tools

Nanometrics to Participate in the 9th Annual CEO Investor Summit 2017: Accredited investor and publishing research analyst event held concurrently with SEMICON West and Intersolar 2017 in San Francisco June 27th, 2017

NMRC, University of Nottingham chooses the Quorum Q150 coater for its reliable and reproducible film thickness when coating samples with iridium June 27th, 2017

New TriboLab CMP Provides Cost-Effective Characterization of Chemical Mechanical Wafer Polishing Processes: Bruker Updates Industry-Standard CP-4 Platform for Most Flexible and Reliable Testing June 27th, 2017

Researchers developed nanoparticle based contrast agent for dual modal imaging of cancer June 21st, 2017

Photonics/Optics/Lasers

Rice U. chemists create 3-D printed graphene foam June 22nd, 2017

New carbon nitride material coupled with ruthenium enhances visible-light CO2 reduction in water June 15th, 2017

Changing the color of laser light on the femtosecond time scale: How BiCoO3 achieves second harmonic generation June 14th, 2017

Learning with light: New system allows optical “deep learning”: Neural networks could be implemented more quickly using new photonic technology June 12th, 2017

Research partnerships

Physicists make quantum leap in understanding life's nanoscale machinery June 27th, 2017

Research accelerates quest for quicker, longer-lasting electronics: UC Riverside-led research makes topological insulators magnetic well above room temperatures June 25th, 2017

Rice U. chemists create 3-D printed graphene foam June 22nd, 2017

Alloying materials of different structures offers new tool for controlling properties June 19th, 2017

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