Filming light and electrons coupled together as they travel under cover

Filming light and electrons coupled together as they travel under cover
An illustration of the experimental set-up described in this study. Credit: F. Carbone/EPFL

In a breakthrough for future optical-electronic hybrid computers, scientists at EPFL have developed an ultrafast technique that can track light and electrons as they travel through a nanostructured surface.

When light couples to electrons on a surface, their concerted motion can travel as a wave guided by the surface geometry itself. These waves are known as "" and might be useful in telecommunications and future computing, where data will be shuttled across processors using light instead of electricity. Aside from being more energy-efficient, these processors could be miniaturized down to the nanoscale to build high-resolution sensors and nanosized signal processing systems. But these processors would be built from stacking different layers of advanced materials and, so far, we don't have a reliable way of tracking the guided light as it moves across their interfaces. EPFL scientists have now done exactly that using a new, ultrafast method. The breakthrough is published today in Nature Communications.

The lab of Fabrizio Carbone at EPFL led the project to create a tiny antenna array that would allow plasmons to travel across an interface. The array consisted of an extremely thin membrane of silicon nitride (50 nm thick) covered with an even thinner film of silver (30 nm thick). The scientists then "punched" a series of nano-holes through the surface that would act as the antennas—the plasmon "hotspots".

The researchers then fired ultrafast laser pulses (light) onto the array to light up the antennas. With a controlled temporal delay, ultrashort electron pulses were then fired across the multilayer stack, to map the plasmons radiated by the antennas at the interface between the silver film and the membrane. Using an ultrafast technique called PINEM, which can "see" surface plasmons, even when they are bound to a buried interface, the scientists were able to actually film the propagation of the guided light and read its spatial profile across the film.

"Trying to see plasmons in these interfaces between layers is a bit like trying to film people in a house from the outside," explains Fabrizio Carbone. "A regular camera won't show you anything; but if you use microwave or a similar energy-tracking imaging, you can see right through the walls."

The current paper paves the way for designing and controlling confined plasmonic fields in multilayered structures, which is key for future optoelectronic devices.

Explore further

Surface plasmons move at nearly the speed of light and travel farther than expected

More information: Tom T. A. Lummen et al, Imaging and controlling plasmonic interference fields at buried interfaces, Nature Communications (2016). DOI: 10.1038/NCOMMS13156
Journal information: Nature Communications

Citation: Filming light and electrons coupled together as they travel under cover (2016, October 11) retrieved 17 September 2019 from
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Oct 25, 2016
it's not just the pretty pictures the info is in the time ordered spectrum, there are only the spherical diametrical fields, you know the material, i.e. number of protons and electrons,the neutron as 1ea, define the obiter count, and the possible orbits from spectra, the rest is computer simulation based upon the continuous set of truths that are measured, motion radiation, stationary static field. Relative to what? Relative to every spherical field center. Hell, you don't even have to change shape, relative to itself, that is, it's all superimposed mathematically and physically by just the particle motion. What do you wish to know, define actuality with a proven theory.

Oct 25, 2016
Don't ignore what you know but cannot measure, like really tiny oscillations you expect to miss, motion inside the nucleus; however we can simulate stability based upon the actual state of any properly defined investigation. So feedback what we see, back into our theory. Speed of a wavelet, in "Free Space" is the transmitted wavelength over it's measured period. The information in the wavelet is always defined relative to the moving center of origin. Each wavelet is completely separable. Heck, we're blind; we don't have to use random theory. What the hell is coupling, magnetic coupling. Dude, what the he(( are you looking at?

Oct 25, 2016
Ping! The media? Definition? Plasmon? Come on, man! Told you not to play with Planck's constant. You are giving me causality, no a result you named in the theory. But, why? Be definitive!

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