Plasmon
[2] Since plasmons are the quantization of classical plasma oscillations, most of their properties can be derived directly from Maxwell's equations.
[3] Plasmons can be described in the classical picture as an oscillation of electron density with respect to the fixed positive ions in a metal.
If the electric field is removed, the electrons move to the right, repelled by each other and attracted to the positive ions left bare on the right side.
It has been shown that the plasmon frequency may occur in the mid-infrared and near-infrared region when semiconductors are in the form of nanoparticles with heavy doping.
[10] They occur at the interface of a material exhibiting positive real part of their relative permittivity, i.e. dielectric constant, (e.g. vacuum, air, glass and other dielectrics) and a material whose real part of permittivity is negative at the given frequency of light, typically a metal or heavily doped semiconductors.
[11] At visible wavelengths of light, e.g. 632.8 nm wavelength provided by a He-Ne laser, interfaces supporting surface plasmons are often formed by metals like silver or gold (negative real part permittivity) in contact with dielectrics such as air or silicon dioxide.
The particular choice of materials can have a drastic effect on the degree of light confinement and propagation distance due to losses.
Up to 40 percent transmission can be achieved at normal incidence with the multilayer system depending on the thickness ratio of copper to nickel.
Multi-parametric surface plasmon resonance can be used not only to measure molecular interactions but also nanolayer properties or structural changes in the adsorbed molecules, polymer layers or graphene, for instance.
A dispersion relation for surface plasmons in the X-ray emission spectra of metals has been derived (Harsh and Agarwal).
Much research goes on first in the microwave range because at this wavelength, material surfaces and samples can be produced mechanically because the patterns tend to be on the order of a few centimeters.
[17] Potential applications of graphene plasmonics mainly addressed the terahertz to midinfrared frequencies, such as optical modulators, photodetectors, biosensors.
[20] Plasmons have also been proposed as a means of high-resolution lithography and microscopy due to their extremely small wavelengths; both of these applications have seen successful demonstrations in the lab environment.
Finally, surface plasmons have the unique capacity to confine light to very small dimensions, which could enable many new applications.
This has led to their use to measure the thickness of monolayers on colloid films, such as screening and quantifying protein binding events.
[21] In 2009, a Korean research team found a way to greatly improve organic light-emitting diode efficiency with the use of plasmons.
[22] A group of European researchers led by IMEC began work to improve solar cell efficiencies and costs through incorporation of metallic nanostructures (using plasmonic effects) that can enhance absorption of light into different types of solar cells: crystalline silicon (c-Si), high-performance III-V, organic, and dye-sensitized.
A graphene-based waveguide is a suitable platform for supporting hybrid plasmon-solitons due to the large effective area and huge nonlinearity.
