Optical computing could benefit from recent development of novel electromagnetic wave

May 22, 2013
Optical computing could benefit from recent development of novel electromagnetic wave
When laser light hits grooves in a thin film of gold (left), it generates surface plasmon polariton waves (cyan dashed lines) that converge and interfere to create a non-diffracting beam (orange). Credit: 2013 Patrice Genevet, Harvard University

An unusual wave that does not spread out as it travels could become a key component in speedy computer chips that use beams of light to carry and process data. Jiao Lin, a physicist at the A*STAR Singapore Institute of Manufacturing Technology, helped to develop the electromagnetic wave, which can travel some 80 micrometers in a straight line without diffracting.

The wave is formed when light hits the surface of a metal, creating ripples in the sea of electrons there. Under certain conditions, the ripples—known as surface plasmons—can couple with the incoming light to create that stick tightly to the as they travel. Known as polaritons, these waves have a shorter wavelength than the light, which makes them more attractive as data carriers.

Although light can zip around a computer much faster than electrons, tend to be much larger than those in conventional circuits—their size is dictated by the wavelength of the light they handle. Using surface plasmon polaritons offers the best of both worlds, explains Lin, because the signals can travel at the speed of light along metal waveguides that are as compact as conventional circuits. Unfortunately, surface plasmon polaritons diffract as they travel over the metal, which erodes the quality of the signals they carry. Previous attempts to prevent this diffraction were moderately successful, but caused the polaritons to veer off course.

The wave developed by Lin and co-workers is a previously unknown solution to Maxwell's equations, which describe how electromagnetic fields behave. Once the team had formulated a of this wave, known as a localized cosine-Gauss beam, Lin helped to turn it into a reality. The team carved two sets of tiny grooves, each roughly 10 micrometers long, into a thin layer of gold stuck to a glass backplate. They slightly angled the grooves to make a chevron pattern (see image).

Shining near-infrared laser light at the grooves generated two surface plasmon polaritons that soon converged and interfered constructively with each other. This resulted in a tightly focused beam that skimmed across the gold without diffracting, covering a much greater distance than previous efforts had achieved. The team tracked the narrow beam as it traveled over the surface using a near-field scanning optical microscope.

Lin says that as well as helping to create faster and more energy efficient computers, the beams could also be used in the laboratory to trap and manipulate nanoparticles.

Explore further: Physicists develop miniature Raman laser sensors for single nanoparticle detection

More information: Lin, J., Dellinger, J., Genevet, P., Cluzel, B., de Fornel, F. & Capasso, F. Cosine-Gauss plasmon beam: A localized long-range nondiffracting surface wave. Physical Review Letters 109, 093904 (2012). prl.aps.org/abstract/PRL/v109/i9/e093904

Related Stories

Needle beam could eliminate signal loss in on-chip optics

Sep 07, 2012

(Phys.org)—An international, Harvard-led team of researchers have demonstrated a new type of light beam that propagates without spreading outwards, remaining very narrow and controlled along an unprecedented ...

Recommended for you

Researchers develop powerful, silicon-based laser

Sep 29, 2014

A silicon-based laser that lases up to a record 111°C, with a threshold current density of 200 A/cm2 and an output power exceeding 100 mW at room temperature, has been demonstrated by collaborating researcher ...

Predicting landslides with light

Sep 29, 2014

Optical fiber sensors are used around the world to monitor the condition of difficult-to-access segments of infrastructure—such as the underbellies of bridges, the exterior walls of tunnels, the feet of dams, long pipelines ...

Studies in laser physics help understand rogue waves

Sep 29, 2014

(Phys.org) —University of Auckland physicist Dr Miro Erkintalo is part of an international team investigating how lasers and optical fibres can be used to understand freakishly large waves on the ocean.

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

vacuum-mechanics
1 / 5 (2) May 22, 2013
The wave developed by Lin and co-workers is a previously unknown solution to Maxwell's equations, which describe how electromagnetic fields behave. Once the team had formulated a mathematical description of this wave, known as a localized cosine-Gauss beam, Lin helped to turn it into a reality.

Not yet, until we could understand 'what the electromagnetic fields' is, in which this could be done via the physical mechanism of Maxwell's electromagnetic field theory, not only the abstract mathematical equations, as follow…
http://www.vacuum...21〈=en
Yogaman
not rated yet May 22, 2013
Why is this appearing on physorg in May, 2013, when the PRL article appeared in Aug, 2012?

Here's a photonics article from Sep, 2012 with more info:

http://www.photon...ID=51790