1. In a waveguide or cavity, one of the various possible patterns of propagating or standing electromagnetic fields.
Note 1: Each mode is characterized by frequency, polarization, electric field strength, and magnetic field strength.
Note 2: The electromagnetic field pattern of a mode depends on the frequency, refractive indices or dielectric constants, and waveguide or cavity geometry.
2. Any electromagnetic… (Read More →)

In an electromagnetic waveguide, the exchange of power among modes.
Note: In a multimode optical fiber, mode coupling reaches statistical equilibrium, i.e., equilibrium mode distribution, after the equilibrium length has been traversed.

An expression of distribution of the irradiance, i.e., the optical power, across the end face of a single-mode fiber.
Note: For a Gaussian power distribution in a single-mode optical fiber, the mode field diameter is that at which the electric and magnetic field strengths are reduced to 1/e of their maximum values, i.e., the diameter at which power is reduced… (Read More →)

A device used to select, reject, or attenuate a certain mode or modes.

Synonym mode scrambler.

[A] description of the conditions under which an information system (IS) operates based on the sensitivity of information processed and the clearance levels, formal access approvals, and need-to-know of its users. Four modes of operation are authorized for processing or transmitting information: dedicated mode, system-high mode, compartmented/ partitioned mode, and multilevel mode. [INFOSEC-99]

In an optical communications link, phase jitter of the signal caused by the combined effects of mode hopping in the optical source and intramodal distortion in the fiber.
Note: Mode hopping causes random wavelength changes which in turn affect the group velocity, i.e., the propagation time. Over a long length of fiber, the cumulative effect is to create jitter, i.e.,… (Read More →)

1. A device for inducing mode coupling in an optical fiber.
2. A device composed of one or more optical fibers in which strong mode coupling occurs.
Note: Mode scramblers are used to provide a modal distribution that is independent of the optical source, for purposes of laboratory or field measurements or tests. Synonym mode mixer.

See cladding mode stripper.

The number of bound modes that an optical fiber is capable of supporting.
Note: The mode volume M is approximately given by V2/2 and (V2/2)[g/(g+2)] respectively for step-index and power-law profile fibers, where g is the profile parameter, and V is the normalized frequency greater than 5.