Short wavelength plasmons observed in nanotubes
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At the heart of the high-technology applications of plasmons is their unique ability to confine the energy of a photon into a spatial dimension smaller than the photon’s wavelength. Now, a team of researchers with Berkeley Lab’s Materials Sciences Div., working at the Advanced Light Source (ALS), has generated and detected plasmons that boast one of the strongest confinement factors ever: the plasmon wavelength is only one hundredth of the free-space photon wavelength.
By focusing infrared light onto the tip of an atomic force microscope, the researchers were able to observe what are called “Luttinger-liquid” plasmons in metallic single-walled nanotubes. A Luttinger-liquid is the theory that describes the flow of electrons through one-dimensional objects, such as a single-walled nanotube (SWNT), much as the Fermi-liquid theory describes the flow of electrons through most two- and three-dimensional metals.
“It is amazing that a plasmon in an individual nanotube, a 1-D object barely a single nanometer in diameter, can even be observed at all,” says Feng Wang, a condensed matter physicist with Berkeley Lab’s Materials Sciences Div. who led this work. “Our use of scattering-type scanning near-field optical microscopy (s-SNOM) is enabling us to study Luttinger-liquid physics and explore novel plasmonic devices with extraordinary sub-wavelength confinement, almost 100 million times smaller in volume than that of free-space photons. What we’re observing could hold great promise for novel plasmonic and nanophotonic devices over a broad frequency range, including telecom wavelengths.”
http://www.rdmag.com/news/2015/07/short-wavel...-nanotubes