effects have inadvertently been 
exploited by glass makers since at 
least the fourth century, for example 
to generate the colours used in 
stained-glass windows in medieval 
cathedrals. 

The scientific investigation of 
plasmonic effects began as early 
as 1899 with theoretical studies by 
Arnold Sommerfeld and experi-
mental observations of plasmonic 
effects in light spectra by Robert 
Wood in 1902. Later that decade, 
J. C. Maxwell Garnett and Gustav 
Mie developed theories explaining 
the scattering effects by metallic 
nanoparticles. However, it was not 
until a number of theoretical studies 
in the 1950s that a more complete 
understanding of SPPs was reached. 
The foundation for the systematic 
experimental study was then laid 
in 1968 by Erich Kretschmann and 
Andreas Otto, who devised methods 
to excite SPPs with prisms attached 
to metal surfaces. 

In the late 1970s, the technologi-
cal exploitation of plasmons began 
with the pioneering discovery by 
Martin Fleischmann and Richard 
Van Duyne of significant enhance-
ments in the Raman scattering of 

The ‘diffraction limit’ of classical 
optics does not allow the localization 
of light into regions that are much 
smaller than its wavelength. As a 
result, the level of integration and 
miniaturization of photonic circuits 
is not even close to that achievable 
in electronics. The technology that 
might close this gap is known as 
‘plasmonics’. Plasmonic structures 
have beaten the diffraction limit, and 
led to advances in spectroscopy and 
sensing, imaging, cancer therapy, 
integrated nano-optics and solar 
cells, to name just a few.

Modern plasmonics started with 
a publication in 1998 by Thomas 
Ebbesen and colleagues, who 
observed a surprisingly efficient 
light transmission through a thin 
metal film with holes ten times 
smaller than the wavelength of 
light. Additionally, more light was 
transmitted through the film than 
was incident onto the area of the 
holes. Eventually, Ebbesen was able 
to explain his observations with 
the properties of surface-plasmon 
polaritons (SPPs).

SPPs consist of photons that 
interact with the surface motions of 
free electrons in metals. Plasmonic 

light by molecules attached to a 
rough silver surface. This effect 
is explored for devices that detect 
molecular concentrations down to 
the single-molecule level.

For applications in photonic 
circuits, the Ebbesen discovery has 
led to efforts aimed at exploiting the 
highly localized nature of plasmons 
to guide light on the nanoscale. 
Furthermore, a plasmon-based ana-
logue to the laser, the spaser, could 
provide a source of coherent light 
below the diffraction limit.

In addition, SPPs are exploited  
in a number of areas, such as  
meta materials (Milestone 21). 
Similarly, plasmonic light concen-
tration can not only enhance light 
absorption in solar cells, but also 
improve the efficiency of light- 
emitting devices.

David Pile,  
Associate Editor, Nature Photonics

ORIGINAL RESEARCH PAPERS Garnett, J. C. M. 
Colours in metal glasses and in metallic films. 
Philos. Trans. R. Soc. Lond. A 203, 385–420 (1904) | 
Mie, G. Beirträge zur Optik trüber Medien, speziell 
kolloidaler Metallosungen. Ann. Phys. 25, 37 
(1908) | Kretschmann, E. & Reather, H. Radiative 
decay of nonradiative surface plasmon excited by 
light. Z. Naturf. 23A, 2135–2136 (1968) | Otto, A. 
Excitation of nonradiative surface plasma waves 
in silver by the method of frustrated total 
reflection. Z. Phys. 216, 398–410 (1968) | 
Fleischmann, M., Hendra, P. J. & McQuillan, A. J. 
Raman spectra of pyridine adsorbed at a silver 
electrode. Chem. Phys. Lett. 26, 163–166 (1974) | 
Jeanmarie, D. L. & Van Duyne, R. P. Surface Raman 
spectroelectrochemistry. Part I. Heterocyclic, 
aromatic, and aliphatic amines adsorbed on the 
anodized silver electrode. J. Electroanal. Chem. 84, 
1–20 (1977) | Ebbesen, T. W., Lezec, H. J., Ghaemi, 
H. F., Thio, T. & Wolf, P. A. Extraordinary optical 
transmission through sub-wavelength hole arrays. 
Nature 391, 667–669 (1998) | Hirsch, L. R. et al. 
Nanoshell-mediated near-infrared thermal 
therapy of tumors under magnetic resonance 
guidance. Proc. Natl Acad. Sci. USA 100, 13549–
13554 (2003) | Bergman, D. J. & Stockman, M. I. 
Surface plasmon amplification by stimulated 
emission of radiation: quantum generation of 
coherent surface plasmons in nanosystems. Phys. 
Rev. Lett. 90, 027402 (2003) | Bozhevolnyi, S. I., 
Volkov, V. S., Devaux, E., Laluet, J. Y. & Ebbesen, T. W. 
Channel plasmon subwavelength waveguide 
components including interferometers and ring 
resonators. Nature 440, 508–511 (2006)
FURTHER READING Raether, H. Surface 
Plasmons on Smooth and Rough Surfaces and on 
Gratings (Springer Verlag, 1988)

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