Photonics Dictionary

In fiber optic communications systems, generally one that operates between 1000 and 1700 nm.

A dispersion relation defined in order to value the reciprocal amount of dispersion. It is defined as the refractivity over the difference in index values of the shortest and longest visible...

Autofluorescence refers to the natural emission of fluorescence exhibited by certain biological structures or molecules when exposed to light. Unlike fluorescence that results from the application of...

A lens aberration that causes axial light rays having different wavelengths to focus at various points along the axis.

A gas laser in which the energy-state transitions between vibrational and rotational states of CO2 molecules give emission at long IR, about 10 µm, wavelengths. The laser can maintain...

A rapid change, as opposed to a long-term drift, of the emission wavelength of an optical source. Chirping is most often observed in pulsed operation of a source.

Chromatic aberration is an optical phenomenon that occurs when different wavelengths (colors) of light are refracted by a lens or optical system, leading to a failure to focus all colors to the same...

The phenomenon observed by A.H. Compton in 1923 -- that some scattered radiation possesses a longer wavelength and correspondingly smaller frequency than the incident radiation. It may be described...

1. In detector technology, the long wavelength at which detector response falls to a set percentage (usually 20 or 50 percent). 2. In fiber optics, the shortest wavelength at which a fiber transmits...

A CCD device for sensing longer wavelengths, such as NIR and IR, that has a deeper depletion region than would be necessary for sensing in the visible wavelength range. Because the depth of charge...

A detector-Dewar assembly typically refers to a combination of a detector and a Dewar flask used in scientific instruments, particularly in the field of infrared spectroscopy or other applications...

A dichroic coating, also known as a dichroic filter or dichroic mirror, is an optical coating designed to selectively transmit or reflect certain wavelengths of light while simultaneously absorbing...

A dichroic mirror, also known as a dichroic beamsplitter or interference filter beamsplitter, is an optical device that selectively reflects or transmits light based on its wavelength. Dichroic...

A diode laser is a type of laser that uses a semiconductor diode as the active medium to generate coherent light. Semiconductor diodes are electronic devices that conduct electricity primarily in one...

With respect to atomic fluorescence spectroscopy, the fluorescence that is emitted by an atom at a spectral line of a wavelength that is longer than that of the stimulating radiation.

Dispersion refers to the phenomenon where different wavelengths (colors) of light travel at different speeds when passing through a medium. This variation in the speed of light for different colors...

A dispersion-shifted fiber (DSF) refers to a type of optical fiber designed to minimize the effects of chromatic dispersion, which is the phenomenon where different wavelengths of light travel at...

A distributed feedback laser (DFB laser) is a type of semiconductor laser diode designed to emit coherent, narrow-bandwidth light with precise control over the wavelength. It achieves this through a...

Optical fiber capable of operating at both a shorter and a longer wavelength.

The total range of wavelengths, extending from the shortest to the longest wavelength or conversely, that can be generated physically. This range of electromagnetic wavelengths extends practically...

In surface height measurement of optics with steep slopes, the use of two short visible wavelengths to synthesize a longer, equivalent wavelength.

A grating with very coarse rulings to match the long wavelengths in the far-infrared region. In the most efficient ruling method, grooves are cut in plane, solid aluminum alloy blanks.

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 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 sensor is a device that uses optical fibers to detect and measure physical, chemical, biological, or environmental parameters. Unlike traditional electrical sensors, fiber optic sensors...

A fiber-coupled LED (light-emitting diode) refers to an LED device that is optically coupled to an optical fiber for the purpose of efficient light transmission. In this configuration, the LED serves...

Fluorescence is a type of luminescence, which is the emission of light by a substance that has absorbed light or other electromagnetic radiation. Specifically, fluorescence involves the absorption of...

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...

Fluorescence microscopy is a specialized optical imaging technique used in biology, chemistry, and materials science to visualize and study specimens that exhibit fluorescence. Fluorescence is the...

Fluorescent proteins are proteins that exhibit the property of fluorescence, which is the ability to absorb light at a specific wavelength and emit light at a longer wavelength. These proteins are...

A fluorophore is a molecule or a portion of a molecule that has the ability to emit light upon excitation by an external energy source, such as ultraviolet or visible light. The process by which a...

FTIR (Fourier transform infrared) spectrometer is a powerful analytical instrument used to obtain an infrared spectrum of absorption or emission of a solid, liquid, or gas sample. It operates based...

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...

The area of optics in which the propagation of light is described by geometrical lines (or rays) governed by Fermat's Principle. Geometrical optics is useful as long as the objects in which the light...

A framework or latticework having an even arrangement of rods, or any other long narrow objects with interstices between them, used to disperse light or other radiation by interference between wave...

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...

The decrease in effect in developable density on a photographic plate formed by a second exposure to radiation having a longer wavelength, usually red or infrared.

An InGaAs (indium gallium arsenide) camera is a type of imaging device that utilizes InGaAs sensors to capture images in the near-infrared (NIR) spectrum. InGaAs is a semiconductor material that is...

An infrared camera, also known as a thermal imaging camera or IR camera, is a device that captures and visualizes the infrared radiation emitted by objects, revealing temperature variations across...

An infrared detector is a device that is used to detect and measure infrared radiation, which lies beyond the visible spectrum of light. These detectors are utilized in various applications,...

A filter exhibiting transparency, absorption or reflectance characteristics specifically for spectral control of wavelengths longer than 700 µm.

An infrared lens is an optical component specifically designed and optimized for transmitting, focusing, or manipulating infrared (IR) radiation within the infrared spectrum. These lenses are used in...

An infrared light source is a device that emits light in the infrared spectrum, which lies beyond the visible spectrum of light. Infrared light has longer wavelengths than visible light and is...