As discussed in a recent overview artlcle, optics meets nanotechnology in plasmonics, an emerging technology that exploits electromagnetic waves tightly coupled to metal surfaces.
Light can be coupled into and out of surface plasmons, in which free-space wavelengths of ~500 nm can be reduced by an order of magnitude and interact with waveguides, apertures, resonators (etc.) having features tens of nanometers in size. Although plasmons typically have short propagation lengths (tens of microns), limited by strong dissipation, devices and complex structures can be built on a sub-micron scale, and there are prospects for offsetting dissipation with gain media like those used in laser diodes.
The ability to make precise, complex, 3D arrangements of metal nanoparticles will be an enabling technology for molecular sensing, optical-frequency circuits, and non-linear optics. This makes plasmonic systems a promising application area for self-assembled composite nanosystems.
A good Nature review article of the fundamental principles, “Surface plasmon subwavelength optics”, can be accessed through links here.