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Curated by RSF Research Staff

Plasmomechanical device modulates, transduces and amplifies light

The interaction of light with matter is a field of active study, with our understanding improving every day at smaller and smaller scales. The previous limit of understanding has now just been broken with the introduction of a plasmomechanical device that allows the interaction of light and matter to be modulated at precise energy ranges below the diffraction limit.

The photoelectric effect demonstrates the interaction of light with matter – where a photon incident upon metal induces the flow of electrons. This effect has been hugely beneficial to our ability to harness and modulate energy. However, to achieve greater speed and more precise effects we need to be able to modulate energy at sub-wavelengths – that is at scales smaller than the wavelength of light in question. The resolution at this scale is limited by the diffraction limit i.e. the theoretical limit of resolution set by the wavelength and the size of the light gathering element - the objective.

Scientists Brian Roxworthy and Vladimir Aksyuk from the National Institute of Standards and Technology (NIST) have developed such a device that is capable of these high speeds and sub-diffraction spatial resolution. Utilizing plasmons - the collective oscillations of electrons – the scientists were successfully able to modulate light, transduce energy and amplify extremely weak electrical and mechanical signals to a much greater precision and at a much faster speed. The device works by coupling a single plasmonic structure in the form of a gold nano-particle to the mechanical vibrations of a device approximately 50 times greater in size. A variable air gap sandwiched between the nano-particle, which is embedded in a silicon nitride cantilever, and a gold film is then used as a means to control the frequency of the nano-particle. The frequency of the plasmons are extremely sensitive to the size and shape of the air gap, allowing for very precise and flexible control.

These findings have huge implications for the advancement of a myriad of technologies from nano-scale laser sources, biochemical detection, particle trapping and manipulation, nonlinear optics, quantum devices and energy harvesting. It will be interesting to see how these devices develop and the level of precision that is achieved!

Amira Val Baker

Article: https://phys.org/news/2018-04-device-modulates-amplifies-tiny.amp

Paper: https://www.osapublishing.org/optica/fulltext.cfm?uri=optica-5-1-71&id=380873

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