Photonics Dictionary

A free-electron laser (FEL) is a type of laser that generates coherent, high-intensity electromagnetic radiation by using a beam of accelerated electrons as the lasing medium. Unlike traditional...

Free-space optics (FSO), also known as optical wireless communication or optical wireless networking, refers to the transmission of data using modulated beams of light through free space (air or a...

Freeform mirrors refer to reflective optical components that deviate from traditional symmetric or rotationally symmetric shapes, such as spheres or paraboloids. Unlike conventional mirrors, which...

Freeform optics refers to the design and fabrication of optical surfaces that do not follow traditional symmetric shapes, such as spheres or aspheres. Unlike standard optical components with...

A frequency comb is a precise and regular series of equally spaced spectral lines, or frequencies, that are generated with great accuracy. The term "frequency comb" is often associated with the Nobel...

The frequency domain is a concept used in signal processing and analysis to represent signals and data in terms of their frequency components. In contrast to the time domain, where signals are...

A Fresnel lens is a type of optical lens that consists of a series of concentric grooves or steps carved into a flat, thin piece of transparent material, typically plastic or glass. This design...

A zone plate in which the zones are alternately transparent and opaque to specific radiation, and coarse enough so that no appreciable diffraction or focusing takes place. The Fresnel zone plate is...

The restricting aperture located at the front of the lens. It is usually defined as the maximum diameter of the entrance cone at the front vertex, for the specified field of view at infinity focus.

The full width at half maximum (FWHM) is a measure used in various fields, particularly in spectroscopy, signal processing, and imaging, to characterize the width or extent of a distribution, peak,...

Functional materials refer to materials that possess specific properties or functionalities that make them suitable for particular applications or purposes. These materials are designed and...

Fused quartz and silica are closely related materials, both composed primarily of silicon dioxide (SiO2), but they are produced through different manufacturing processes and have distinct properties...

1. The combination of the effects of two or more stimuli in any given sense to form a single sensation. With respect to vision, the perception of continuous illumination formed by the rapid...

A GaAlAs laser is a type of semiconductor laser diode that emits light in the near-infrared region of the electromagnetic spectrum. It is composed of layers of gallium, aluminum, and arsenic, hence...

Gain-switching is a technique used in lasers to generate short pulses of light by modulating the gain of the laser medium. This method is distinct from Q-switching and mode-locking, two other common...

Gallium arsenide phosphide (GaAsP) is a semiconductor alloy composed of gallium (Ga), arsenic (As), and phosphorus (P). It is commonly used in the fabrication of optoelectronic devices, particularly...

Gallium arsenide (GaAs) is a compound semiconductor material composed of gallium (Ga) and arsenic (As). It belongs to the III-V group of semiconductors and has a zincblende crystal structure. GaAs is...

Gallium nitride (GaN) is a compound made up of gallium (Ga) and nitrogen (N). It is a wide-bandgap semiconductor material that exhibits unique electrical and optical properties. Gallium nitride is...

A galvanometric scanner, also known as a galvanometer scanner or galvo scanner, is a type of optical scanning device used to rapidly and precisely direct a laser beam or other light source to...

GaN (gallium nitride) distributed feedback (DFB) lasers refer to a specific type of semiconductor laser based on Gallium Nitride materials and designed with a distributed feedback structure. These...

Gallium nitride-based light-emitting diodes (GaN-based LEDs) are semiconductor devices that emit light when an electric current passes through them. These LEDs are constructed using gallium nitride...

A specific gas-filled tube designed to illustrate the luminous effects of discharges through rarefied gases.

In image processing, mathematical operations that change spatial geometry, as for instance scaling, translating, rotating or otherwise manipulating the perspective. Also called geometric manipulation.

Germanium crystal refers to a crystalline form of the element germanium (Ge), which is a metalloid and semiconductor commonly used in various electronic and optical applications. Germanium crystals...

Germicidal ultraviolet (GUV) refers to a specific range of UV radiation that has disinfectant properties capable of killing or inactivating microorganisms, including bacteria, viruses, and fungi. The...

1. A faint second image caused by reflection that is sometimes seen when observing through an optical instrument. 2. With respect to spectroscopy, a false image of a spectral line formed by...

GigE, short for gigabit Ethernet, refers to a standard for high-speed Ethernet communication, capable of transmitting data at rates of up to 1 gigabit per second (Gbps), or 1000 megabits per second...

A noncrystalline, inorganic mixture of various metallic oxides fused by heating with glassifiers such as silica, or boric or phosphoric oxides. Common window or bottle glass is a mixture of soda,...

A device that detects and measures the quantity of exposure to nuclear radiation. It uses a special glass rod that fluoresces when placed under ultraviolet radiation after its exposure to nuclear...

A furnace used to heat glass materials. It may be a small laboratory-type furnace for small-scale experiments or large enough to hold gas-fired tanks for the commercial mass production of glass....

The process whereby a spectacle lens is placed in a frame.

The specular reflection of individual parts of a surface.

A photometer for measuring gloss by comparing the specular reflectance to that from a perfect specular reflector.

Gold colloid aggregates refer to clusters or assemblies of gold nanoparticles suspended in a liquid medium. These aggregates are formed when individual gold nanoparticles come together due to various...

A spectrometer or autocollimator used to measure prism angles.

The term gradient-index profile refers to a specific type of refractive index distribution within an optical material. In optics, the refractive index of a material describes how much the speed of...

Gram-positive bacteria are a group of bacteria that have a thick cell wall composed primarily of a substance called peptidoglycan. This thick peptidoglycan layer retains a stain called crystal violet...

A grating beamsplitter is an optical device that utilizes the principles of diffraction to split a beam of light into multiple beams, often redirecting them at specific angles. It is based on the...

A specific, right-angle prism having a transmission grating replicated on its hypotenuse face and used in applications requiring a system that can produce in-line viewing for one wavelength.