- About Us
- Career Center
- Nano-Social Network
- Nano Consulting
- My Account
|This scanning electron image of a nano colorsorter with the vertical bowtie antenna shifted 5 nanometers (nm) to the left of center. In (a) the bowtie has been excited at 820 nm and in (b) at 780 nm. The two modes are spectrally and spatially distinct while maintaining nanoscale mode volumes.|
Berkeley Lab researchers at the Molecular Foundry have created bowtie-shaped antennae that function as the first tunable nano colorsorters, able to capture, filter and steer light at the nanoscale.
Looking sharp and looking for light - Berkeley Lab researchers have engineered a new class of bowtie-shaped devices that capture, filter and steer light at the nanoscale. These "nano-colorsorter" devices act as antennae to focus and sort light in tiny spaces, a useful technique for harvesting broadband light for color-sensitive filters and detectors.
Currently, optical fibers employ light to transport data with very high bandwidth, but the technique hits a roadblock as light is squeezed into smaller and smaller photonic circuits. This roadblock is the diffraction limit - a fundamental restriction in concentrating photons into regions smaller than half their wavelength. In contrast, electronic devices are readily fashioned at nanometer scales; however, electronic data transfer operates at frequencies far below those for fiber optics, with much lower bandwidth, reducing the amount of data carried.
A recent technology, coined "plasmonics," crowds electromagnetic waves into metal structures with dimensions much smaller than the wavelength of light for transmitting data at optical frequencies, marrying the best aspects of optical and electronic communications. A particularly promising class of structures for enhancing this crowding effect is nanoscale optical antennae made of gold, which leverage plasmonic behavior to efficiently capture and confine light in miniscule dimensions.
"Like the antenna on your TV or radio, optical nanoantennas efficiently catch and concentrate energy, but the wavelengths are much smaller," says Jim Schuck, a staff scientist withn the Molecular Foundry, a U.S. Department of Energy (DOE) national user facility at Berkeley Lab that provides support to nanoscience researchers around the world.
"We've made the first engineered and nanofabricated stucture for nanoscale light distribution that can ship and manipulate ultra-confined optical information with a knob you can easily tune-the energy or color of light," says Schuck, who works in the Foundry's Imaging and Manipulation of Nanostructures Facility.
Molecular Foundry post-doctoral researcher Zhaoyu Zhang, working with Schuck and Nanofabrication Facility Director Stefano Cabrini, fabricated nanoantennas from four equilateral triangles of gold lithographically patterned to create a ‘cross' geometry.
Breaking the symmetry of this cross-shaped device affects its primary resonance mode - a property best illustrated by the shattering of a champagne flute when it encounters a musical tone of the right pitch. In these cross nanoantennas, the resonant modes correspond to different frequencies, or colors, of light.
"We can now control the plasmonic properties of these devices by introducing asymmetry, and we find red and blue light is literally sent left and right," says Zhang. "By pushing the limits of manipulating light in a smaller volume, we can move information to one place or another quickly and efficiently, which is important for fast, color-sensitive photodetection. "
Indeed, shifting the vertically aligned bowtie in the cross nanoantenna just five nanometers left of center generates two resonance modes, producing a two-color filter. The team further demonstrated this effect by breaking other symmetries of the bowties, leading to a three-color filter. This symmetry breaking gives scientists the ability to "auto-tune" a device to a desired set of colors or energies, crucial for filters and other detectors. Using the nanofabrication capabilities available at the Foundry, the scientists plan to explore adjusting the size, shape, and position of the bowties to optimize device properties. For example, thousands of bowties could be packed in an area less than one millimeter across, enabling large, but ultrafast, detector arrays.
"Our findings lend insight into the link between simple symmetry breaking and the coherent coupling properties of localized plasmons, providing a pathway for engineering intricate devices that can control light in extremely confined spaces," Schuck adds.
A scientific paper reporting this research entitled "Manipulating nanoscale light fields with the asymmetric bowtie nano-colorsorter," by Zhaoyu Zhang, Alexander Weber-Bargioni, Shiwei Wu, Scott Dhuey, Stefano Cabrini and James Schuck, appears in Nano Letters and is available in Nano Letters online.
Work at the Molecular Foundry was supported by the Director, Office of Science, Office of Basic Energy Sciences, Division of Materials Science and Engineering, of the DOE under Contract No. DE-AC02-05CH11231.
The Molecular Foundry is one of the five DOE Nanoscale Science Research Centers (NSRCs), premier national user facilities for interdisciplinary research at the nanoscale. Together the NSRCs comprise a suite of complementary facilities that provide researchers with state-of-the-art capabilities to fabricate, process, characterize and model nanoscale materials, and constitute the largest infrastructure investment of the National Nanotechnology Initiative. The NSRCs are located at DOE's Argonne, Brookhaven, Lawrence Berkeley, Oak Ridge and Sandia and Los Alamos National Laboratories.
For more information about the research of James Schuck, visit the Web at
For more information about the research of Stefano Cabrini visit the Web at foundry.lbl.gov/six/nanofabrication/staff-Stefano_Cabrini.html
For more information about The Molecular Foundry, visit the Web at foundry.lbl.gov
For more information about the DOE NSRCs, visit the Web at nano.energy.gov.
About Berkeley Lab
Berkeley Lab is a U.S. Department of Energy national laboratory located in Berkeley, California. It conducts unclassified scientific research for DOE’s Office of Science and is managed by the University of California.
For more information, please click here
Copyright © Berkeley LabIf 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.
|Related News Press|
News and information
Display technology/LEDs/SS Lighting/OLEDs
First single-enzyme method to produce quantum dots revealed: Biological manufacturing process, pioneered by three Lehigh University engineers, produces equivalent quantum dots to those made chemically--but in a much greener, cheaper way May 9th, 2016
Simple attraction: Researchers control protein release from nanoparticles without encapsulation: U of T Engineering discovery stands to improve reliability and fabrication process for treatments to conditions such as spinal cord damage and stroke May 28th, 2016
Doubling down on Schrödinger's cat May 27th, 2016
The next generation of carbon monoxide nanosensors May 26th, 2016
Dartmouth team creates new method to control quantum systems May 24th, 2016
Electronic device detects molecules linked to cancer, Alzheimer's and Parkinson's: An inexpensive portable biosensor has been developed by researchers at Brazil's National Nanotechnology Laboratory with FAPESP's support May 20th, 2016
Making organs transparent to improve nanomedicine (video) May 13th, 2016
Attosecond physics: A switch for light-wave electronics May 24th, 2016
We’ll Leave the Lights On For You: Photonics advances allow us to be seen across the universe, with major implications for the search for extraterrestrial intelligence, says UC Santa Barbara physicist Philip Lubin - See more at: http://www.news.ucsb.edu/2016/016805/we-ll-leave-li May 17th, 2016