Photonics Dictionary

A type of erasable data storage device that uses a medium deposited on the disc in two layers, each dyed to absorb a different wavelength of laser light. To record data, the lower layer is heated by...

An Er:YAG laser is a type of solid-state laser that uses a crystal made of erbium-doped yttrium aluminum garnet (Er:Y3Al5O12) as the gain medium. The erbium (Er) ions are introduced into the crystal...

An optical fiber that can be used to amplify an optical input. Erbium rare earth ions are added to the fiber core material as a dopant in typical levels of a few hundred parts per million. The fiber...

An etalon is an optical device that consists of two parallel reflecting surfaces separated by a precise and known distance. It operates based on the principle of optical interference and is used to...

An excimer laser is a type of ultraviolet laser that emits short pulses of light in the ultraviolet spectrum. The term excimer is derived from excited dimer, reflecting the nature of the gain medium...

In laser pumping, parasitic absorption that occurs at certain wavelengths, decreasing pump efficiency and gain.

An exciton is a quasiparticle that represents the bound state of an electron and a hole in a solid-state material, typically a semiconductor or an insulator. In simpler terms, an exciton is a paired...

Extreme ultraviolet (EUV) refers to a specific range of electromagnetic radiation in the ultraviolet part of the spectrum. EUV radiation has wavelengths between 10 and 124 nanometers, which...

Wavelengths between 400 and 1400 nm (VIS to NIR) are focused onto the retina by the cornea. Because the retina is sensitive to light, these wavelengths can be damaging even at low energies. It is the...

An f-theta lens, also known as an f-theta scan lens or simply an f-theta lens system, is a specialized optical component used in laser scanning systems, particularly in laser marking, engraving, and...

A multiple-beam interferometer, usually consisting of two flat plates, with high reflective ability. The plates are set parallel to one another by spacers so that lightwaves may bounce back and forth...

A device in which slab geometry internally compensates for thermal-optic distortion; the solid host material -- glass or Nd:YAG -- is in the form of a rectangular slab with plane parallel faces. The...

A laser with output over a wide range of wavelengths spanning the far-infrared region of the spectrum (30 to 1000 µm); typically, it consists of a metal or dielectric waveguide one to two...

A FAC lens, or fast axis collimation lens, is an optical component used in laser diode systems to collimate the fast axis of laser emission. Laser diodes emit light in two main axes: the fast axis,...

A femtosecond laser is a type of laser that emits ultrashort pulses of light with durations on the order of femtoseconds, where one femtosecond is equal to 10-15 seconds. These lasers are capable of...

A fiber Bragg grating (FBG) is a type of optical filter that is inscribed or "written" into the core of an optical fiber. It consists of a periodic modulation of the refractive index along the length...

A fiber laser is a type of laser in which the active gain medium is an optical fiber doped with rare-earth ions such as erbium, ytterbium, or neodymium. Fiber lasers generate coherent light through...

A fiber optic preform is a cylindrical glass rod or tube used as the starting material for manufacturing optical fibers. It serves as the precursor from which optical fibers are drawn. The process of...

A fiber optic spectrometer is a device used for measuring the spectral content of light. It utilizes optical fibers to transmit light from a source to a spectrometer unit, where the light is...

Flow cytometry is a powerful technique used in biology and medicine for the quantitative analysis of the physical and chemical characteristics of cells and particles suspended in a fluid. The method...

Fluorescence lifetime imaging (FLIM) is an advanced imaging technique that provides information about the lifetime of fluorescence emissions from fluorophores within a sample. Unlike traditional...

Fluoride fibers are optical fibers made from fluoride-based materials, typically fluoride glasses or crystalline fluoride compounds. These fibers are characterized by their unique optical properties,...

A single-particle scattering technique in which an incident laser beam is tightly focused by means of lenses to yield a focal spot in the scattering material with a diameter on the order of the...

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...

A technique used in holography that involves the mixing of lasers of different wavelengths to produce a beam of shorter wavelength.

In a lens, the square of the radius of its aperture divided by the product of the focal length and the wavelength. It measures the importance of diffraction in the image formed by the lens. A small...

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...

Fusion ignition refers to the point in a controlled nuclear fusion reaction where the energy released by the fusion reactions becomes self-sustaining, leading to a continuous release of energy...

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...

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...

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...

One of the first lasers to find practical application. Generally, the pumping mechanism is an electric discharge, although some high-power forms employ chemical reaction or gas compression and...

The area of optics that deals with the propagation of Gaussian laser beams in free space, or any general medium - i.e. lenses- under the paraxial (small divergence angle) approximations. Gaussian...

A GRIN (gradient index) lens is a type of optical lens that utilizes a gradient in refractive index across its volume rather than having a uniform refractive index like conventional lenses. This...

1. The value on either the leading or the trailing edge of a laser pulse at which the power is one-half of its maximum value. 2. The wavelength at which a filter is transmitting one-half of its peak...

Harmonic generation refers to a nonlinear optical process in which incoming photons interact with a material and produce new photons at integer multiples of the frequency of the incoming photons....

A helium-neon (HeNe) laser is a type of gas laser that emits visible red light at a wavelength of 632.8 nm. It operates based on the principle of stimulated emission of photons from excited helium...

High harmonic generation (HHG) refers to a nonlinear optical process in which intense laser light interacts with a gaseous medium, typically an atom or a molecule, to produce harmonics of the...

Holmium lasers are a type of medical laser that utilizes holmium-doped crystals as the gain medium. The term holmium laser is often associated with a specific type of laser used in urology for...

A holographic camera, also known as a holographic imaging system or holographic recorder, is a specialized device used to capture 3D holographic images of objects or scenes. Unlike conventional...

A holographic grating is a type of diffraction grating that is produced using holographic recording techniques. It consists of a periodic structure of alternating transparent and opaque regions,...

A component used to modify light rays by diffraction; the HOE is produced by recording the interference pattern of two laser beams and can be used in place of lenses or prisms where diffraction...

In the context of optical materials, the term "impurity level" refers to the presence of foreign atoms or molecules within the material that deviate from its regular or intrinsic composition. These...

Indium phosphide (InP) is a compound semiconductor material composed of indium (In) and phosphorus (P). It belongs to the III-V group of semiconductors, where elements from groups III and V of the...

Inertial confinement fusion (ICF) is a method of achieving nuclear fusion, a process where two atomic nuclei combine to release energy. In the case of inertial confinement fusion, the fusion reaction...