Photonics Dictionary: P

1. In a photonic interconnect, the number of detectors in a given area. Detectors spaced too closely may give rise to crosstalk. 2. In the cross section of a fiber optic bundle, the ratio of fiber...

The ratio of the active core area of a fiber bundle to the total area at its light-emitting or receiving end.

Color sensitivity extended to cover the entire visible spectrum out to the red.

The condition in which the index of refraction in an optical fiber varies as a parabolic function of the radius.

In a fiber optic guided missile, the point at which the optical fiber pays out from the bobbin on which it is wound.

A thin, stretched plastic membrane cemented to a rigid supporting ring. It may be coated to act as a beamsplitter, for example, in a color camera; it is so thin that no perceptible image doubling...

A Peltier cooler, also known as a thermoelectric cooler (TEC) or thermoelectric module, is a solid-state device that uses the Peltier effect to transfer heat between two electrical junctions. It can...

In astronomy, the main lobe of an antenna pattern that has a small angular extent in two mutually perpendicular directions. Invisible in space, it would resemble a searchlight beam.

The term perovskite refers to a specific crystal structure commonly found in various materials. Perovskite structures have a cubic arrangement of oxygen ions, forming a framework within which other...

The grinding and polishing of rock samples, to a thickness of less than 0.05 mm, for study with petrographic microscopes. When mounted on a slide and protected with a cover, these samples, examined...

A phage, short for bacteriophage, is a type of virus that infects and replicates within bacteria. Phages are composed of genetic material (either DNA or RNA) surrounded by a protein coat. They are...

In optics and photonics, "phase" refers to a property of electromagnetic waves, such as light, that describes the position of a wave at a given point in time within its oscillation cycle. More...

Phase contrast microscopy is an optical microscopy technique that enhances the contrast of transparent and colorless specimens, making it possible to visualize fine details and internal structures...

Phase distortion refers to a change in the phase relationships between different frequency components of a signal. In the context of signal processing, it occurs when the phase response of a system...

In optics and photolithography, a phase mask refers to a device that modifies the phase of light waves passing through it. The phase mask is used to control the spatial distribution of the light's...

Phase matching is a crucial concept in the field of optics, particularly in nonlinear optics and the generation of coherent light. It refers to the condition where the phases of two or more waves,...

In biology, particularly genetics and evolutionary biology, the phenotype refers to the observable characteristics or traits of an organism, resulting from the interaction of its genetic makeup...

A phonon is a quantum of vibrational energy associated with the periodic motion of atoms or molecules in a crystalline lattice. In simpler terms, phonons are quanta of lattice vibrations in a solid...

A chemical substance that exhibits fluorescence when excited by ultraviolet radiation, x-rays or an electron beam. The amount of visible light is proportional to the amount of excitation energy. If...

A light therapy that utilizes nonionizing light sources, including lasers, LEDs, and broadband light, in the visible and infrared spectrum. It is a nonthermal process involving endogenous...

Photobleaching is a phenomenon in which the fluorescence of a fluorophore (a fluorescent molecule or dye) is permanently reduced or eliminated upon prolonged exposure to light. This process occurs...

Photocathodes are specialized materials or surfaces that exhibit the photoelectric effect, wherein the absorption of photons leads to the emission of electrons. When photons with sufficient energy...

The term photochemical pertains to chemical processes or reactions that are initiated or influenced by the absorption of light. Photochemical reactions involve the interaction of light, often in the...

A chemical compound that exhibits a reversible change in its absorption spectrum upon irradiation with given wavelengths of light.

Photochromic refers to a property exhibited by certain materials, typically organic compounds or dyes, which undergo reversible changes in color when exposed to light. Specifically, photochromic...

The reversible change in the absorption spectrum of certain compounds upon irradiation with a given wavelength of light.

A film of material that exhibits varying conductivity based upon its absorption of varying amounts of photon radiation.

The conductivity increase exhibited by some nonmetallic materials, resulting from the free carriers generated when photon energy is absorbed in electronic transitions. The rate at which free carriers...

Photoelastic equipment and supplies refer to instruments and materials used in photoelasticity, a technique used to analyze stress distribution and behavior in materials. photoelastic equipment...

In optics, the double refraction that is produced when stress is applied to a transparent material. Plastics, which are especially photoelastic, can be formed into models of structures that are...

The process of determining, with the aid of plane-polarized light, the stress distribution in materials under complex systems of loading.

A device used to count objects that pass a given point by allowing each object to obstruct a beam of light falling on a photocell. Slow counting rates can be recorded by a mechanical counter, but...

A technique proposed for studying the atomic structure of crystals by measuring the interference pattern generated when the crystal is illuminated by a burst of finely tuned x-rays. The resulting...

The direct influence of light on the magnetic susceptibility of particular materials.

Photocells of various kinds used to measure photometric quantities; i.e., intensity, luminance and illuminance. Meter readings are used to express illuminance and, by calibration, to measure...

Photometry is the branch of science that deals with the measurement of light, particularly in terms of its intensity and the way the human eye perceives it. It involves the quantification of visible...

An instrument in which visible light beyond the critical angle from a metallurgical microscope is focused on a reference surface. A certain fraction of the incident light tunnels through air to the...

The property exhibited by a substance having electrical conductivity that decreases as the intensity of the incident visible radiant energy increases.

Photonic crystals are artificial structures or materials designed to manipulate and control the flow of light in a manner analogous to how semiconductors control the flow of electrons. Photonic...

A photonic integrated circuit (PIC) is a compact and integrated device that incorporates multiple photonic components and functions on a single chip, similar to the way electronic integrated circuits...

The technology of generating and harnessing light and other forms of radiant energy whose quantum unit is the photon. The science includes light emission, transmission, deflection, amplification and...

Photonics contract manufacturing refers to the outsourcing of the production of photonics-related components, devices, or systems to specialized manufacturing firms. Photonics involves the...

A holographic plate coated by photopolymeric mixtures that are composed of one or more monomers and a photoredox catalyst sensitized to visible light. The material becomes a plastic solid when...

Photosynthetically active radiation (PAR) is the 400- to 700-nm region (visible light) of the electromagnetic spectrum that is absorbed and used by the plant for photosynthesis. Also referred to as...

A camera equipped with angular scales in altitude and azimuth. The scale readings are imprinted on the film when an exposure is made. The exact point indicated by the scale readings is shown by...

Phototherapy is a medical treatment that involves the use of light to treat various conditions, particularly those related to the skin or mood disorders. There are different types of phototherapies,...