History, current developments, and future directions of near-field optical science

This paper reviews the science of the optical near-field (ONF), which is created and localized in a nanometer-sized material (NM) or on its surface. It is pointed out that work on near-field optics was started in order to break through the diffraction limit in optical microscopy and had already come to an end without giving answers to the essential questions on the origin of the near-field optical interaction. However, recent studies have reincarnated these studies and identified the ONF as an off-shell quantum field. Based on this identification, a novel science called off-shell science has started on the basis that the dispersion relation between energy and momentum is invalid for the ONF. This quantum field is called the dressed photon because it is created as a result of the interaction between photons and electrons (or excitons) in a NM and, thus, it accompanies the energies of electrons or excitons. In reviewing current developments, this paper presents fifteen novel phenomena that are contrary to the common views in conventional optical science. Novel technologies developed by applying these phenomena are also reviewed. These include: nanometer-sized optical devices, nano-fabrication technology, and energy conversion technology. High-power Si light emitting diodes, Si lasers, and SiC polarization rotators are reviewed as examples of electrical to optical energy conversion. For future directions, this paper also reviews novel theoretical studies that have commenced recently by relying on physical and mathematical bases.