Nanophotonics
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Nanophotonics or nano-optics is the study of the behavior of
The term "nano-optics", just like the term "optics", usually refers to situations involving
Background
Normal optical components, like lenses and microscopes, generally cannot normally focus light to nanometer (deep
Application
Nanophotonics researchers pursue a very wide variety of goals, in fields ranging from biochemistry to electrical engineering to carbon-free energy. A few of these goals are summarized below.
Optoelectronics and microelectronics
If light can be squeezed into a small volume, it can be absorbed and detected by a small detector. Small photodetectors tend to have a variety of desirable properties including low noise, high speed, and low voltage and power.[6][7][8]
Small
version of lasers.Integrated circuits are made using photolithography, i.e. exposure to light. In order to make very small transistors, the light needs to be focused into extremely sharp images. Using various techniques such as immersion lithography and phase-shifting photomasks, it has indeed been possible to make images much finer than the wavelength—for example, drawing 30 nm lines using 193 nm light.[10] Plasmonic techniques have also been proposed for this application.[11]
Heat-assisted magnetic recording is a nanophotonic approach to increasing the amount of data that a magnetic disk drive can store. It requires a laser to heat a tiny, subwavelength area of the magnetic material before writing data. The magnetic write-head would have metal optical components to concentrate light at the right location.
Miniaturization in
Solar cells
Controlled release of anti-cancer therapeutics
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.[14]
Spectroscopy
Using nanophotonics to create high peak intensities: If a given amount of light energy is squeezed into a smaller and smaller volume ("hot-spot"), the intensity in the hot-spot gets larger and larger. This is especially helpful in
Microscopy
One goal of nanophotonics is to construct a so-called "
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. It involves raster-scanning a very sharp tip or very small aperture over the surface to be imaged.[2]
Near-field microscopy refers more generally to any technique using the near-field (see below) to achieve nanoscale, subwavelength resolution. In 1987, Guerra (while at the Polaroid Corporation) achieved this with a non-scanning whole-field Photon tunneling microscope.[18] In another example, dual-polarization interferometry has picometer resolution in the vertical plane above the waveguide surface.[citation needed]
Optical data storage
Nanophotonics in the form of subwavelength near-field optical structures, either separate from the recording media, or integrated into the recording media, were used to achieve optical recording densities much higher than the diffraction limit allows.[19] This work began in the 1980s at Polaroid Optical Engineering (Cambridge, Massachusetts), and continued under license at Calimetrics (Bedford, Massachusetts) with support from the NIST Advanced Technology Program.
Band-gap engineering
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. In 2008, Thulin and Guerra published modeling that showed not only bandgap shift, but also band-edge shift, and higher hole mobility for lower charge recombination.[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.
Silicon nanophotonics
Silicon photonics is a silicon-based subfield of nanophotonics in which nano-scale structures of the optoelectronic devices realized on silicon substrates and that are capable to control both light and electrons. They allow to couple electronic and optical functionality in one single device. 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.[21]
As of 2016 the research of in silicon photonics spanned light modulators,
Principles
Plasmons and metal optics
Metals are an effective way to confine light to far below the wavelength. 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. For a similar reason, visible light can be confined to the nano-scale via nano-sized metal structures, such as nano-sized structures, tips, gaps, etc. Many nano-optics designs look like common microwave or radiowave circuits, but shrunk down by a factor of 100,000 or more. After all, radiowaves, microwaves, and visible light are all electromagnetic radiation; they differ only in frequency. So other things equal, a microwave circuit shrunk down by a factor of 100,000 will behave the same way but at 100,000 times higher frequency. [23] [24] This effect is somewhat analogous to a lightning rod, where the field concentrates at the tip. The technological field that makes use of the interaction between light and metals is called
For example, researchers have made nano-optical dipoles and Yagi–Uda antennas following essentially the same design as used for radio antennas.[26][27]
Metallic parallel-plate
Near-field optics
In nanophotonics, strongly localized radiation sources (
Nanophotonics is primarily concerned with the near-field evanescent waves. For example, a superlens (mentioned above) would prevent the decay of the evanescent wave, allowing higher-resolution imaging.
Metamaterials
Metamaterials are artificial materials engineered to have properties that may not be found in nature. They are created by fabricating an array of structures much smaller than a wavelength. The small (nano) size of the structures is important: That way, light interacts with them as if they made up a uniform, continuous medium, rather than scattering off the individual structures.
See also
- ACS Photonics
- Photonics
- Photonics Spectra journal
- Ultraperformance Nanophotonic Intrachip Communications
References
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- ^ a b "Research Discovery By Ethiopian Scientist At IBM". Tadias Magazine. Retrieved 2010-03-15.
- ^ Dumé, Isabelle (2010-03-04). "Avalanche photodetector breaks speed record". Physics World.
- ^ Hand, Aaron. "High-Index Lenses Push Immersion Beyond 32 nm". Archived from the original on 2015-09-29. Retrieved 2014-09-27.
- PMID 22355690.
- ^ "IBM Research | IBM Research | Silicon Integrated Nanophotonics". Domino.research.ibm.com. 2010-03-04. Retrieved 2010-03-15.
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- ^ ISSN 2192-8614.
- ^ "Silicon Nanophotonics: Basic Principles, Present Status, and Perspectives, Second Edition". Routledge & CRC Press. Retrieved 2021-08-31.
- ISBN 981-02-4365-0.
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- ^ van Hulst, Niek. "Optical Nano-antenna Controls Single Quantum Dot Emission". 2physics.
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- PMID 21468019.
- ISBN 9780511794193.
External links
- ePIXnet Nanostructuring Platform for Photonic Integration
- Optically induced mass transport in near fields
- "Photonics Breakthrough for Silicon Chips: Light can exert enough force to flip switches on a silicon chip," by Hong X. Tang, IEEE Spectrum, October 2009
- Nanophotonics, nano-optics and nanospectroscopy A. J. Meixner (Ed.) Thematic Series in the Open AccessBeilstein Journal of Nanotechnology