Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Small Optical Force Can Budge Nanoscale Objects

19.11.2009
With a bit of leverage, Cornell researchers have used a very tiny beam of light with as little as 1 milliwatt of power to move a silicon structure up to 12 nanometers. That’s enough to completely switch the optical properties of the structure from opaque to transparent.

The technology could have applications in the design of micro-electromechanical systems (MEMS) – nanoscale devices with moving parts – and micro-optomechanical systems (MOMS) which combine moving parts with photonic circuits, said Michal Lipson, associate professor of electrical and computer engineering.

The research by postdoctoral researcher Gustavo Wiederhecker, Long Chen Ph.D. ’09, Alexander Gondarenko, Ph.D. ’10, and Lipson appears now in the online edition of the journal Nature and will appear in a forthcoming print edition.

Light can be thought of as a stream of particles that can exert a force on whatever they strike. The sun doesn’t knock you off your feet because the force is very small, but at the nanoscale it can be significant. “The challenge is that large optical forces are required to change the geometry of photonic structures,” Lipson explained.

But the researchers were able to reduce the force required by creating two ring resonators – circular waveguides whose circumference is matched to a multiple of the wavelength of the light used – and exploiting the coupling between beams of light traveling through the two rings.

A beam of light consists of oscillating electric and magnetic fields, and these fields can pull in nearby objects, a microscopic equivalent of the way static electricity on clothes attracts lint. This phenomenon is exploited in “optical tweezers” used by physicists to trap tiny objects. The forces tend to pull anything at the edge of the beam to be pulled toward the center.

When light travels through a waveguide whose cross-section is smaller than its wavelength some of the light spills over, and with it the attractive force. So parallel waveguides close together, each carrying a light beam, are drawn even closer, rather like two streams of rainwater on a windowpane that touch and are pulled together by surface tension.

The researchers created a structure consisting of two thin, flat silicon nitride rings about 30 microns (millionths of a meter) in diameter mounted one above the other and connected to a pedestal by thin spokes. Think of two bicycle wheels on a vertical shaft, but each with only four thin, flexible spokes. The ring waveguides are three microns wide and 190 nanometers (nm – billionths of a meter) thick, and the rings are spaced 1 micron apart.

When light at a resonant frequency of the rings, in this case infrared light at 1533.5 nm, is fed into the rings, the force between the rings is enough to deform the rings by up to 12 nm, which the researchers showed was enough to change other resonances and switch other light beams traveling through the rings on and off. When light in both rings is in phase – the peaks and valleys of the wave match – the two rings are pulled together. When it is out of phase they are repelled. The latter phenomenon might be useful in MEMS, where an ongoing problem is that silicon parts tend to stick together, Lipson said.

An application in photonic circuits might be to create a tunable filter to pass one particular optical wavelength, Wiederhecker suggested.

The work is supported by the National Science Foundation (NSF) and the Cornell Center for Nanocale Systems. Devices were fabricated at the Cornell NanoScale Science and Technology Facility, also supported by NSF.

Blaine Friedlander | Newswise Science News
Further information:
http://www.cornell.edu

More articles from Physics and Astronomy:

nachricht Tune your radio: galaxies sing while forming stars
21.02.2017 | Max-Planck-Institut für Radioastronomie

nachricht Breakthrough with a chain of gold atoms
17.02.2017 | Universität Konstanz

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Impacts of mass coral die-off on Indian Ocean reefs revealed

21.02.2017 | Earth Sciences

Novel breast tomosynthesis technique reduces screening recall rate

21.02.2017 | Medical Engineering

Use your Voice – and Smart Homes will “LISTEN”

21.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>