One-dimensional nanoscale structures, such as multilayer optical coatings and distributed Bragg reflectors, have long been staples of optical design and engineering. This report is restricted to the new developments that arise from the ability to control structures at the nanoscale in multiple dimensions (two-dimensional and three-dimensional photonic crystals, reduced dimensionality, and quantum confinement), to control both the magnetic and the electrical response of materials (metamaterials), or to manipulate nanoscale structures for enhanced field concentration (plasmonics). The areas of nanophotonics discussed in this report are characterized by their different physical nanoscale phenomena and the scale (relative to a wavelength) of the modulation of the index of refraction in the nanoscale material or system. Following are the four areas of nanophotonics selected by the committee as most relevant to cover in this report:
Photonic crystals—in which the spatial index modulation is on the order of a wavelength;
Metamaterials—in which the structural elements are much smaller than the wavelength, permitting an effective medium approach to the optical properties;
Plasmonics—in which manipulation of light at the nanoscale is based on the properties of surface plasmons arising from metal free-electron response (negative permeability); and
Confined semiconductor structures—whose physics is driven by reduced dimensionality and quantum confinement.
The committee identified several overarching themes regarding the accessibility of nanophotonics technology in a 10-to-15-year time frame. First, nanophotonics will provide foundational building blocks for military capabilities, as discussed by the committee in addressing nanophotonics in relation to major strategic/critical military technologies. Second, advances in nanophotonics will enable new systems. A third theme noted by the committee is that of commercial markets pushing advances in nanophotonics to an increasingly greater degree while DOD and intelligence community agencies concurrently play lesser roles as drivers of this field.
Specific technological advances in nanophotonics are expected to contribute to major scientific and applications developments. The following list of such innovations is representative, not exhaustive:
The surmounting of optical wavelength limitations in electronic devices, allowing unprecedented resolution in imaging applications, as well as the true integration of photonic and electronic functionalities. Implications include the ability to truly realize “optics on a chip” through the combination of nanoelectronics and nanophotonics, enhancing a range of capabilities from information technologies and advanced computing to advanced sensing. Success in this area would also enable breakthroughs in imaging systems and microscopies where the diffraction limit to resolution will be overcome in many important cases.
The confinement of optical-matter interactions to the nanoscale, where the quantum mechanical regime dominates interactions and yields size-dependent, novel electronic and optical properties. Progress in this area would enable a wide range of “quantum technologies” such as quantum computing, quantum cryptography for secure communications, and advanced sensing capabilities. Other applications include tunable and efficient light sources, detectors, and other optical elements with enhanced and reconfigurable functionality.