Photonics Dictionary

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 complex filter that uses polarization and interference to transmit light that is nearly monochromatic.

All formulas that present the index of refraction as a function of a wavelength of electromagnetic radiation. Also called dispersion equation, Cauchy formula, Hartmann formula.

A type of glass optical fiber that provides low pulse dispersion over a broad portion of the light spectrum and as a result can operate at 1300-nm and 1550-nm wavelengths simultaneously.

Operation in which the dispersion of a pulse limits the distance between repeaters in optical systems. Waveguide and material dispersion can make recognition of a pulse impossible.

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...

Dispersion that occurs when the medium's index of refraction decreases as the frequency of the propagating light increases. For a given medium, some wavelength ranges may produce anomalous dispersion...

Recombination of only the light that is correctly dispersed by the first stage of a polychromator through its wide intermediate slit (common during Thomson scattering experimentation), which is...

The process whereby white light is separated into its component wavelengths. Light beams of different wavelengths are separated from each other by undergoing a different angular deviation. Prisms and...

The dispersion attributable to the wavelength dependence of the refractive index of the material used in any optical application.

Synonym for multimode distortion. Also called mode dispersion.

Synonym (regarded by some as erroneous) for multimode distortion, which see.

Dispersion characterized by an increasing index of refraction in the medium as the frequency of the propagating light increases towards the resonant frequency of the medium. Normal dispersion occurs...

In an optical waveguide, that dispersion attributable to the variation of refractive index profile with wavelength. The profile variation has two contributing factors: variation in refractive index...

For each mode in an optical waveguide, the term used to describe the process by which an electromagnetic signal is distorted by virtue of the dependence of the phase and group velocities on...

In a single-mode optical fiber, the wavelength that causes material dispersion and waveguide dispersion to cancel each other. In a multimode fiber, loose term for the wavelength at which there is a...

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...

A form of roof prism used to invert an image. The prism has faces cut normal to the optical axis; therefore, the prism may be placed within the optical path of a system and invert the image without...

Device which measures the index of refraction of glass as well as the dispersion over visible range.

A reflecting prism that inverts the image. The image is reflected four times internally and emitted laterally. The prism is cut normal to the optical axis while the image is internally reflected from...

An achromat, in the context of optics, refers to a type of lens or lens system designed to reduce chromatic aberration. Chromatic aberration is an optical phenomenon where different colors of light...

Blaze height typically refers to a parameter in the context of diffraction gratings, which are optical devices consisting of a series of closely spaced parallel grooves or slits. The blaze height is...

A transparent powdered solid immersed in a liquid or plastic of similar refractive index but widely different dispersion; used to isolate narrow spectral regions.

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...

A coherent fiber bundle (CFB), also known as a coherent fiber optic bundle, is an assembly of multiple optical fibers arranged in a specific geometric pattern to maintain the spatial coherence of...

The dispersion of a light ray striking the surface of a biaxial crystal, in which the resulting rays are reflected in a conical manner.

A liquid, usually of a specific refractive index and dispersion, serving as an interface between two solids to form a complete light transmission system.

One of the two principal types of optical glass, the other being flint glass. Crown glass is harder than flint glass, and has a lower index of refraction and lower dispersion. Both types are used in...

The naturally occurring crystalline form of silicon dioxide. It is slightly birefringent and exhibits rotary dispersion of light rays transmitted along the crystal axis, both right-hand and left-hand...

An organizational method used in optical design computer programs. The technique produces one number (merit function) to measure the state of correction of an optical system. This number, which is...

A telescope that corrects dispersion and spherical aberration through the use of one or more lenses, usually smaller than the objective lens, that are positioned at a distance from the objective lens.

Exhibiting the characteristic of materials that are electrical insulators or in which an electric field can be sustained with a minimum dispersion of power. They exhibit nonlinear properties, such as...

A spectrograph that uses a diffraction grating as its dispersive element in place of a prism, and yields greater resolving power, more dispersion and a linear spectrum.

A diffraction grating is an optical component consisting of a surface with a periodic structure of equally spaced, parallel grooves or rulings. These rulings act as an array of closely spaced slits...

A measure of the dispersive properties of a glass. The relative dispersion is defined as: where C, D, and F refer to the material's index of refraction at the three chief Fraunhofer lines in the...

A grating that serves to provide higher resolution and dispersion than the average grating, and still has a greater free spectral range than either the Fabry-Perot etalon or the reflection echelon.

The occurrence of very large rotations in transparent materials at weak magnetic fields as predicted in the classical dispersion theory. This effect was discovered by Mavaluso and Corbino in 1898 in...

The entrance slit, also known simply as the slit, is an essential component in optical instruments such as spectrometers and monochromators. It is a narrow opening or aperture through which light...