Nanophotonics
It often involves dielectric structures such as nanoantennas, or metallic components, which can transport and focus light via surface plasmon polaritons.
[5] Nanophotonics researchers pursue a very wide variety of goals, in fields ranging from biochemistry to electrical engineering to carbon-free energy.
[6][7][8] Small lasers have various desirable properties for optical communication including low threshold current (which helps power efficiency) and fast modulation[9] (which means more data transmission).
[13] Nanophotonics has also been implicated in aiding the controlled and on-demand release of anti-cancer therapeutics like adriamycin from nanoporous optical antennas to target triple-negative breast cancer and mitigate exocytosis anti-cancer drug resistance mechanisms and therefore circumvent toxicity to normal systemic tissues and cells.
[15][16] One goal of nanophotonics is to construct a so-called "superlens", which would use metamaterials (see below) or other techniques to create images that are more accurate than the diffraction limit (deep subwavelength).
[17] This was accomplished by coupling a transparent phase grating having 50 nm lines and spaces (metamaterial) with an immersion microscope objective (superlens).
Near-field scanning optical microscope (NSOM or SNOM) is a quite different nanophotonic technique that accomplishes the same goal of taking images with resolution far smaller than the wavelength.
In 2002, Guerra (Nanoptek Corporation) demonstrated that nano-optical structures of semiconductors exhibit bandgap shifts because of induced strain.
In the case of titanium dioxide, structures on the order of less than 200 nm half-height width will absorb not only in the normal ultraviolet part of the solar spectrum, but well into the high-energy visible blue as well.
[20] The band-gap engineered titanium dioxide is used as a photoanode in efficient photolytic and photo-electro-chemical production of hydrogen fuel from sunlight and water.
Such devices find a wide variety of applications outside of academic settings,[21] e.g. mid-infrared and overtone spectroscopy, logic gates and cryptography on a chip etc.
This was originally used in radio and microwave engineering, where metal antennas and waveguides may be hundreds of times smaller than the free-space wavelength.
[26][27] Metallic parallel-plate waveguides (striplines), lumped-constant circuit elements such as inductance and capacitance (at visible light frequencies, the values of the latter being of the order of femtohenries and attofarads, respectively), and impedance-matching of dipole antennas to transmission lines, all familiar techniques at microwave frequencies, are some current areas of nanophotonics development.
For example, at optical frequency, metals behave much less like ideal conductors, and also exhibit interesting plasmon-related effects like kinetic inductance and surface plasmon resonance.
These sources can be decomposed into a vast spectrum of plane waves with different wavenumbers, which correspond to the angular spatial frequencies.
