Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

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

Iran to Hold 3rd Int'l Engineering Materials, Metallurgy Conference October 25th, 2014

Haydale Secures Exclusive Development and Supply Agreement with Tantec A/S: New reactors to be built and commissioned by Tantec A/S represent another step forward towards the commercialisation of graphene October 24th, 2014

QuantumWise guides the semiconductor industry towards the atomic scale October 24th, 2014

SUNY Polytechnic Institute Invites the Public to Attend its Popular Statewide 'NANOvember' Series of Outreach and Educational Events October 23rd, 2014

Govt.-Legislation/Regulation/Funding/Policy

Novel Rocket Design Flight Tested: New Rocket Propellant and Motor Design Offers High Performance and Safety October 23rd, 2014

Strengthening thin-film bonds with ultrafast data collection October 23rd, 2014

Brookhaven Lab Launches Computational Science Initiative:Leveraging computational science expertise and investments across the Laboratory to tackle "big data" challenges October 22nd, 2014

Bipolar Disorder Discovery at the Nano Level: Tiny structures found in brain synapses help scientists better understand disorder October 22nd, 2014

Possible Futures

Imaging electric charge propagating along microbial nanowires October 20th, 2014

Superconducting circuits, simplified: New circuit design could unlock the power of experimental superconducting computer chips October 18th, 2014

Nanocoatings Market By Product Is Expected To Reach USD 8.17 Billion By 2020: Grand View Research, Inc. October 15th, 2014

Perpetuus Carbon Group Receives Independent Verification of its Production Capacity for Graphenes at 140 Tonnes per Annum: Perpetuus Becomes the First Manufacturer in the Sector to Allow Third Party Audit October 7th, 2014

Academic/Education

SUNY Polytechnic Institute Invites the Public to Attend its Popular Statewide 'NANOvember' Series of Outreach and Educational Events October 23rd, 2014

First Canada Excellence Research Chair gets $10 million from the federal government for oilsands research at the University of Calgary: Federal government announces prestigious research chair to study improving oil production efficiency October 19th, 2014

Raytheon, UMass Lowell open on-campus research institute: Industry leader’s researchers to collaborate with faculty, students to move key technologies forward through first-of-its-kind partnership October 11th, 2014

SUNY Colleges of Nanoscale Science and Engineering and National Institute for Occupational Safety and Health Announce Expanded Partnership October 2nd, 2014

Self Assembly

NYU Researchers Break Nano Barrier to Engineer the First Protein Microfiber October 23rd, 2014

NIST offers electronics industry 2 ways to snoop on self-organizing molecules October 22nd, 2014

‘Designer’ nanodevice could improve treatment options for cancer sufferers October 22nd, 2014

Crystallizing the DNA nanotechnology dream: Scientists have designed the first large DNA crystals with precisely prescribed depths and complex 3D features, which could create revolutionary nanodevices October 20th, 2014

Nanomedicine

NYU Researchers Break Nano Barrier to Engineer the First Protein Microfiber October 23rd, 2014

Iranian Scientists Apply Nanotechnology to Produce Surgery Suture October 23rd, 2014

RF Heating of Magnetic Nanoparticles Improves the Thawing of Cryopreserved Biomaterials October 23rd, 2014

Sopping up proteins with thermosponges: Researchers develop novel nanoparticle platform that proves effective in delivering protein-based drugs October 22nd, 2014

Sensors

MEMS & Sensors Technology Showcase: Finalists Announced for MEMS Executive Congress US 2014 October 23rd, 2014

Journal Nanotechnology Progress International (JONPI), 2014, Volume 5, Issue 1, pp 1-24 October 22nd, 2014

Imaging electric charge propagating along microbial nanowires October 20th, 2014

Graphenea opens US branch October 16th, 2014

Announcements

Iran to Hold 3rd Int'l Engineering Materials, Metallurgy Conference October 25th, 2014

Haydale Secures Exclusive Development and Supply Agreement with Tantec A/S: New reactors to be built and commissioned by Tantec A/S represent another step forward towards the commercialisation of graphene October 24th, 2014

QuantumWise guides the semiconductor industry towards the atomic scale October 24th, 2014

Strengthening thin-film bonds with ultrafast data collection October 23rd, 2014

Tools

Haydale Secures Exclusive Development and Supply Agreement with Tantec A/S: New reactors to be built and commissioned by Tantec A/S represent another step forward towards the commercialisation of graphene October 24th, 2014

National Synchrotron Light Source II Achieves 'First Light' October 23rd, 2014

Advancing thin film research with nanostructured AZO: Innovnano’s unique and cost-effective AZO sputtering targets for the production of transparent conducting oxides October 23rd, 2014

NIST offers electronics industry 2 ways to snoop on self-organizing molecules October 22nd, 2014

Photonics/Optics/Lasers

Physicists build reversible laser tractor beam October 20th, 2014

Magnetic mirrors enable new technologies by reflecting light in uncanny ways October 16th, 2014

New VDMA Association "Electronics, Micro and Nano Technologies" founded: Inaugural Meeting in Frankfurt/Main, Germany October 15th, 2014

Nanodevices for clinical diagnostic with potential for the international market: The development is based on optical principles and provides precision and allows saving vital time for the patient October 15th, 2014

Research partnerships

NYU Researchers Break Nano Barrier to Engineer the First Protein Microfiber October 23rd, 2014

Nanoparticle technology triples the production of biogas October 23rd, 2014

RF Heating of Magnetic Nanoparticles Improves the Thawing of Cryopreserved Biomaterials October 23rd, 2014

Brookhaven Lab Launches Computational Science Initiative:Leveraging computational science expertise and investments across the Laboratory to tackle "big data" challenges October 22nd, 2014

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







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE