All articles starting with P
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Photonic spin Hall effect
The photonic spin Hall effect (PSHE) is an optical phenomenon in which left- and right-handed circularly polarized light shifts in opposite directions at an interface.
Photonic time crystals
Photonic time crystals are artificial media whose permittivity varies periodically in time, giving momentum bandgaps that exponentially amplify light, proposed by Zeng and colleagues in 2017.
Photonic time interface
A photonic time interface is an abrupt, spatially uniform change in a medium's electromagnetic properties, such as its refractive index, the temporal counterpart of a spatial interface between two materials.
Photonic topological insulator
A photonic topological insulator (PTI) is an optical structure, usually a photonic crystal, where light travels in protected edge states along its boundary while the bulk stays insulating.
Photonic Weyl points
Photonic Weyl points are isolated points in a photonic system's band structure where two frequency bands touch linearly in all three momentum dimensions, first observed in 2015.
Photonic wire bonding
Photonic wire bonding (PWB) is a chip-packaging technique that connects photonic integrated circuits on different chips, fibers, or lasers using 3D polymer waveguides written by direct laser lithography.
Photonic-crystal fiber
Photonic-crystal fiber is an optical fiber with a periodic array of air holes along its length, first demonstrated at the University of Southampton in 1996.
Photonic-crystal selective emitters for thermophotovoltaics
Photonic-crystal selective emitters for thermophotovoltaics are engineered thermal emitters whose periodic structure is tuned to emit only the wavelengths a thermophotovoltaic cell can convert, raising efficiency and power density.
Photonics
Photonics is the applied science and engineering of manipulating photons for technology, as electronics does electrons, with devices such as lasers, LEDs, and optical fibers.
Photonics West
Photonics West is SPIE's annual six-day winter conference and exhibition for optics and photonics, held at the Moscone Center in San Francisco since 2010, drawing over 24,000 attendees.
Photoperiod
Photoperiod is the daily length of the light phase; photoperiodism is the response to day and night length, discovered by Garner and Allard in 1918 with Maryland Mammoth tobacco and Biloxi soybeans, governing flowering, diapause, and seasonal reproduction.
Photoperiodism
Photoperiodism is the biological response to relative day and night length, discovered by Garner and Allard (1920); it governs plant flowering classes and, via melatonin and pars tuberalis TSH, seasonal breeding in mammals.
Photophobia
Photophobia is abnormal light sensitivity causing eye discomfort or pain, a symptom of migraine (85-90% of patients), dry eye, blepharospasm, and TBI, mediated by melanopsin ipRGCs and treated by addressing the cause plus FL-41 tinted lenses.
Photophoretic levitation
Photophoretic levitation is the lifting of an object by light, which heats it relative to the surrounding gas so gas molecules push it upward; demonstrated levitation includes centimeter-scale plates for exploring Earth's mesosphere.
Photophoretic trapping
Photophoretic trapping is the stable three-dimensional confinement of a light-absorbing particle in air, using forces from uneven heating of the particle by light, where optical tweezers struggle.
Photophosphorylation
Photophosphorylation: light-driven ATP synthesis from ADP and phosphate in photosynthetic electron transport, via Mitchell's chemiosmotic proton motive force; cyclic, noncyclic, and pseudocyclic pathways in chloroplasts and bacteria.
Photoplethysmogram
Photoplethysmogram (PPG): noninvasive optical signal of arterial blood volume changes, basis of pulse oximetry and wearable heart-rate sensors; transmission or reflectance mode, green/red/IR light, used for heart rate, SpO2, rhythm screening.
Photopolymerization
Photopolymerization is a polymer chemistry method that uses ultraviolet, visible, or near-infrared light to convert liquid monomers into solid polymers, underpinning UV-curable coatings and dental resin composites.
Photorealism
Photorealism, also called Superrealism or Hyperrealism, is an art movement begun 1968–69 in New York and California in which artists such as Richard Estes, Chuck Close, and Audrey Flack painted from photographs with airbrushed, brushstroke-free precision.
Photoreceptor cell
Photoreceptor cells (rods and cones) are retinal neurons that convert light into electrical signals via a G-protein phototransduction cascade; rods detect single photons in dim light, cones mediate bright-light, color, high-acuity vision.
Photoreceptor disk component PRCD
PRCD (photoreceptor disc component) is a 54-amino-acid, ~6 kDa rhodopsin-binding protein of unknown function found only in photoreceptor outer segment discs; its C2Y mutation causes canine progressive rod-cone degeneration and human retinitis pigmentosa 36.
Photoredox activation of alkylsilicates
Photoredox activation of alkylsilicates is a synthetic method that uses visible-light photoredox catalysts to oxidize alkylbis(catecholato)silicate salts, cleaving the silicon–carbon bond to release alkyl radicals that form C(sp3)–C(sp2) bonds with nickel catalysts under mild, base-free conditions.
Photoredox alkene dicarbofunctionalization
Photoredox alkene dicarbofunctionalization is a family of visible-light reactions adding two distinct carbon groups across an alkene in one photochemical operation, typically via radical-polar crossover.
Photoredox Birch-type reduction
A photoredox Birch-type reduction is a light-driven variant of the Birch reduction in which a visible-light photocatalyst, rather than alkali metal in ammonia, converts arenes to 1,4-cyclohexadienes.
Photoredox catalysis
Photoredox catalysis is a synthetic method in which a photocatalyst absorbs visible light and transfers a single electron to organic substrates, forming bonds under mild conditions.
Photoredox decarboxylative borylation of redox-active esters
Photoredox decarboxylative borylation of redox-active esters is a radical reaction that converts alkyl carboxylic acids into versatile alkyl boronates, reported in 2017 by the Baran, Aggarwal, and Li groups.
Photoredox decarboxylative C–C bond formation
Photoredox decarboxylative C–C bond formation is a set of visible-light reactions in which carboxylic acids lose carbon dioxide to form radicals that build new carbon–carbon bonds under mild conditions.
Photoredox decarboxylative trifluoromethylation
Photoredox decarboxylative trifluoromethylation is a visible-light reaction in which trifluoroacetic acid releases carbon dioxide to form trifluoromethyl radicals that bond to arenes, used in drug discovery.
Photoredox deracemization of amines
Photoredox deracemization of amines is a set of light-driven catalytic methods that convert racemic amines entirely into a single enantiomer using visible-light photocatalysts, developing rapidly since 2018.
Photoredox direct C–H arylation of heteroarenes
Photoredox direct C–H arylation of heteroarenes joins aryl groups to heteroarene C–H bonds using aryl radicals from visible-light photoredox catalysts, as first shown metal-free with eosin Y in 2012.