1. An essential technical requirement for items, materials, or services, including the procedures to be used to determine whether the requirement has been met.
Note: Specifications may also include requirements for preservation, packaging, packing, and marking.
2. An official document intended primarily for supporting procurement, which document clearly and accurately describes the essential technical requirements for items, materials, or services,… (Read More →)

An industry agreed-upon location where a set of specifications would apply, for example, the node in the originating network where specification occurs. [After T1.118-1992]

Synonym modal noise.

In optical systems, a field-intensity pattern produced by the mutual interference of partially coherent beams that are subject to minute temporal and spatial fluctuations.
Note: In a multimode fiber, a speckle pattern results from a superposition of mode field patterns. If the relative modal group velocities change with time, the speckle pattern will also change with time. If differential mode… (Read More →)

See spectral width.

For a specified bandwidth of radiation consisting of a continuous frequency spectrum, the total power in the specified bandwidth divided by the specified bandwidth.
Note: Spectral density is usually expressed in watts per hertz.

Irradiance per unit wavelength interval at a given wavelength, usually expressed in watts per unit area per unit wavelength interval.

A narrow range of emitted or absorbed wavelengths.

Of an optical fiber, a plot of attenuation as a function of wavelength.
Note: Spectral loss curves must be normalized with respect to distance before meaningful comparison among fibers can be made.

The degree to which a signal is monochromatic.