Physicists report technology with potential for sub-micron optical switches

March 30, 2015
Surface plasmons are propagating electronic oscillations localized to metal-insulator (e.g. gold-air) interfaces. Gap plasmons (GPs) arise when two such interfaces are separated by a narrow gap across the insulator layer, transversely confining the electromagnetic energy in an MIM (metal-insulator-metal) waveguide. In this illustration, a free-space excitation laser (vertical light on the right) couples to GPs (alternating red/blue light) in a gold/air/gold nanofabricated waveguide. A grating is used to match the laser light momentum with to a GP. The GP propagates through the waveguide under free-floating micro-beams in the top gold layer (color coded to show depth). When the beams are electrically actuated towards the bottom gold layer, the effective refractive index of the waveguide increases under the beams, phase-retarding the GP. Credit: Brian Dennis, Rutgers University

A team that includes Rutgers University and National Institute of Standards and Technology scientists believes that a technology it is reporting this week in Nature Photonics could result in optical switches with sub-square-micron footprints, potentially allowing densely packed switching fabrics on a chip.

These dimensions contrast with established optical switching technologies based on other technologies, such as MEMS, , and silicon and electro-optic polymer plasmonic technologies, that have active elements in scales up to hundreds of microns.

The scientists have shown that an optical signal can be modulated in a 200 nanometer-high waveguide. The signal's phase is modulated as it passes through an air gap between two gold layers, when a force generated by the device slightly deforms the top gold layer.

The scientists propose that when one of these modulators is placed next to a similar static device, it could act as a 2x2 switch, based on evidence reported elsewhere of coupling between adjacent waveguides. The technology could also be useful for electrically tunable plasmonic devices.

Their paper describes "compact nanomechanical plasmonic phase modulators." The scientists experimentally verified such devices in a 23 micron-long waveguide with a gap in the range of 200 nm, but they make a case based on computer modeling that the waveguides can be scaled to as little as 1 micron long with a 20 nm gap, without significant loss. This means optical switches could be scaled closer to electronic dimensions.

Explore further: World-record micrometer-sized converter of electrical into optical signals

More information: Compact nanomechanical plasmonic phase modulators, DOI: 10.1038/nphoton.2015.40

Related Stories

Recommended for you

Lightning, with a chance of antimatter

November 22, 2017

A storm system approaches: the sky darkens, and the low rumble of thunder echoes from the horizon. Then without warning... Flash! Crash!—lightning has struck.

How the Earth stops high-energy neutrinos in their tracks

November 22, 2017

Neutrinos are abundant subatomic particles that are famous for passing through anything and everything, only very rarely interacting with matter. About 100 trillion neutrinos pass through your body every second. Now, scientists ...

Quantum internet goes hybrid

November 22, 2017

In a recent study published in Nature, ICFO researchers led by ICREA Prof. Hugues de Riedmatten report an elementary "hybrid" quantum network link and demonstrate photonic quantum communication between two distinct quantum ...

Enhancing the quantum sensing capabilities of diamond

November 22, 2017

Researchers have discovered that dense ensembles of quantum spins can be created in diamond with high resolution using an electron microscopes, paving the way for enhanced sensors and resources for quantum technologies.

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

tonybudz
not rated yet Mar 30, 2015
Tunable Plasmonic devices, finally.

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.