Abstract
We fabricate and characterize a metal-dielectric nanostructure with an effective refractive index in the visible spectral range. Light is excited in the material at deep subwavelength resolution by a 30-keV electron beam. From the measured spatially and angle-resolved emission patterns, a vanishing phase advance, corresponding to an effective and , is directly observed at the cutoff frequency. The wavelength at which this condition is observed can be tuned over the entire visible or near-infrared spectral range by varying the waveguide width. This plasmonic nanostructure may serve as a new building block in nanoscale optical integrated circuits and to control spontaneous emission as experimentally demonstrated by the strongly enhanced radiative optical density of states over the entire structure.
- Received 18 May 2012
DOI:https://doi.org/10.1103/PhysRevLett.110.013902
© 2013 American Physical Society
Viewpoint
Metal-Coated Waveguide Stretches Wavelengths to Infinity
Published 2 January 2013
A zero refractive index at optical frequencies, as demonstrated in a new nanoscale waveguide, enables opportunities for better control and enhancement of light propagation in waveguides, as well as development of photonic nanocircuits.
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