Interaction between light and sound in nanoscale waveguide

February 17, 2015
Interaction between light and sound in nanoscale waveguide
Both light (left) and sound (right) are trapped in a nanoscale silicon core.

Scientists from Ghent University and imec announce today that they demonstrated interaction between light and sound in a nanoscale area. Their findings elucidate the physics of light-matter coupling at these scales – and pave the way for enhanced signal processing on mass-producible silicon photonic chips.

In the last decade, the field of has gained increasing attention as a key driver of lab-on-a-chip biosensors and of faster-than-electronics communication between computer chips. The technology builds on tiny structures known as silicon photonic wires, which are roughly a hundred times narrower than a typical human hair. These nanowires carry optical signals from one point to another at the . They are fabricated with the same technological toolset as electronic circuitry.

Fundamentally, the wires work only because moves slower in the silicon core than in the surrounding air and glass. Thus, the light is trapped inside the wire by the phenomenon of total internal reflection. Simply confining light is one thing, but manipulating it is another. The issue is that one light beam cannot easily change the properties of another. This is where comes into the picture: it allows some photons to control other photons.

Publishing in Nature Photonics, researchers from the Photonics Research Group of Ghent University and imec report on a peculiar type of light-matter interaction. They managed to confine not only light but also sound to the . The sound oscillates ten billion times per second: far more rapid than human ears can hear. They realized that the sound cannot be trapped in the wire by total internal reflection. Unlike light, sound moves faster in the core than in the surrounding air and glass. Thus, the scientists sculpted the environment of the core to make sure any vibrational wave trying to escape it would actually bounce back. Doing so, they confined both light and sound to the same nanoscale waveguide core – a world's first observation.

Trapped in that incredibly small area, the light and vibrations strongly influence each other: light generates sound and shifts the color of light, a process known as stimulated Brillouin scattering. The scientists exploited this interaction to amplify specific colors of light. They anticipate this demonstration to open up new ways to manipulate optical information. For instance, light pulses could be converted into sonic pulses and back into light – thereby implementing much-needed delay lines. Further, the researchers expect that similar techniques can be applied to even smaller entities such as viruses and DNA. These particles have unique acoustic vibrations that may be used to probe their global structure.

Explore further: Engineers make sound loud enough to bend light on a computer chip

More information: R. Van Laer, B. Kuyken, D. Van Thourhout and R. Baets. "Interaction between light and highly confined hypersound in a silicon photonic nanowire." Nature Photonics (2015)

Related Stories

Researchers use sound to slow down, speed up, and block light

January 28, 2015

How do you make an optical fiber transmit light only one way? Researchers from the University of Illinois at Urbana-Champaign have experimentally demonstrated, for the first time, the phenomenon of Brillouin Scattering Induced ...

Ripple patterns in silicon can enhance solar cell efficiency

January 14, 2015

A*STAR scientists have produced a uniform nanoscale ripple pattern over a wide area on a silicon surface by scanning a femtosecond laser beam across it. Given that a rippled surface is much less reflective than a smooth surface, ...

Breakthrough lights up metamaterials

January 16, 2015

City College of New York led-team has successfully demonstrated how to both enhance light emission and capture light from metamaterials embedded with light emitting nanocrystals. The breakthrough, headed by physicist Dr. ...

Graphene surfaces on photonic racetracks

July 28, 2014

In an article published in Optics Express, scientists from The University of Manchester describe how graphene can be wrapped around a silicon wire, or waveguide, and modify the transmission of light through it.

Recommended for you

New metamaterial paves way for terahertz technologies

October 24, 2016

A research team led by UCLA electrical engineers has developed an artificial composite material to control of higher-frequency electromagnetic waves, such as those in the terahertz and far-infrared frequencies.

Light-driven atomic rotations excite magnetic waves

October 24, 2016

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how the ultrafast light-induced modulation of the atomic positions ...

The quantum sniffer dog

October 24, 2016

As humans, we sniff out different scents and aromas using chemical receptors in our noses. In technological gas detection, however, there are a whole host of other methods available. One such method is to use infrared lasers, ...

Scientists manipulate surfaces to make them invisible

October 21, 2016

Most lenses, objectives, eyeglass lenses, and lasers come with an anti-reflective coating. Unfortunately, this coating works optimally only within a narrow wavelength range. Scientists at the Max Planck Institute for Intelligent ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.