Electronics have inspired photonics for optical circuits, and by connecting these two sciences, plasmonics circuits have been understood in the last few years.
FREMONT, CA: Silicon dioxide, also called silica, is commonly found in nature, sand, or quartz and is one of the amplest chemical compounds on earth. Humans discovered how to transform silica into silicon, and today almost all of our modern technology relies on this single starting material.
The four basic elements of electronics are
(1) electrons as carrier vectors
(2) electrical cables and circuits
Progress in photonics offers the opportunity to substitute electron flow, for transmission and computing, with a photonic flow or a plasmonic flow, utilizing the interaction between the surface electrons of nanostructured circuits and photons.
The data carrier vectors in photonics can be photons, solitons, light balls, or plasmons. Lasers and spasers are the optical equivalents of electrical generators; optical waveguides and optical fibres act as transport cables, and monsters and optical transistors are the equivalents of electrical switches & electronic transistors.
The plasmon is a quasi-particle associated with free electron density plasma oscillations. The association of this particle, arising from existing electrons present in the material and injected photons, offers at least two unique, greatly important benefits:
1) the possibility to transmit information with a higher frequency (about ∼100 THz) and
2) the capability to confine light in very small dimension objects.
These new photonic structures are similar to those found in electronics. For example, new promising three-layer oxide/metal/oxide electrodes are collected in transparent flexible electronics and third-generation solar cells. We seek these same structures in photonics for plasmonic waveguides. This is also the matter for organic solar cells and organic waveguides. Electronics have also inspired photonics for optical circuits, and by connecting these two sciences, plasmonics circuits have been understood in the last few years.
By comparing the fundamental elements from these two sciences – electrical cables vs optical fibres and plasmonic waveguides; the electron in electronics vs. the photon, soliton, and plasmon in photonics; electrical transistors vs. optical transistors and plasmonsters; electrical circuits vs. optical circuits; electrical generators vs. pulsed lasers and spasers – we observe that photonics has built up, step by step, all the tools already accessible in electronics.
These similarities cause the idea that, in the future, we may be able to substitute devices that employ an electronic flow (mobile phones, computers, displays, etc.) with equivalent devices that utilize a photonic or a plasmonic flow. Moreover, in the case of a photonic flow, it may be feasible to take the gain of the ultimate photon generator as an energy source, the Sun.
This presents a common problem in applying photovoltaic systems: the night–necessitating energy storage. Still, if we think on a global scale, light is always available (the earth rotates). Therefore, one of the biggest challenges of taking the edge of solar energy is storing the energy and creating a global photovoltaic energy network. Optical fiber networks are already positioned and could represent a primary step in connecting future plasmonic computers.
While present electronics and photonics are based on sand (silicon and silicon dioxide), carbon, in bulk and graphene form, might be the next element of choice. Graphene is a really interesting material for electronic applications as a transparent electrode with very good mechanical properties, with new transfer techniques enabling deposition on large area flexible surfaces.
Because of the absence of an optical band gap, graphene absorbs all photons at any wavelength. Still, if incident light intensity becomes strong enough because of the Pauli blocking principle, the produced carriers fill the valence bands, avoiding further excitation of electrons at the valance band.
Therefore this property could potentially be exploited to realize short and very intense light pulses lasers with a wide optical response ranging from ultra-violet, visible, infrared to terahertz. These lasers might be the tomorrow of pulsed signal photonic generators. Furthermore, graphene's structure specificity and charge transport properties open new research possibilities through graphene nanoplasmonics.
While humanity has shown it can thrive on technologies derived from sand, it rests on seeing whether the same can be stated of carbon. But perhaps the major issues are; if photonic informatics becomes a reality, will we still need electricity? And what will the solar-powered devices of tomorrow resemble?
Today we transform various forms of energy into electricity to meet most of our needs. But, will it be possible to avoid transforming the energy into electricity and directly exploit solar energy for all our requirements? For heating, we can and often already use solar energy directly without transforming it. If light storage is practicable through plasmons, laser cavities, or light trapping, as in the black body model, it will be likely to directly use solar energy for lighting.
Optical manipulation and optical engine ideas have already been experimentally proved, and the progress in photonics with optical circuits, optical transistors, etc., has revealed that photonic or plasmonic informatics might be possible too. If laser propulsion can be accomplished and optical engines work, we may also have motors working with light.