Macro-bending loss
Loss due to large bends in the fibre. Bending of an optical fibre or fibre bundle at a radius comparatively larger than the fibre diameter. Macrobends are larger tha microbends, being visible, and generally caused by bending the cable beyond the specified bend radius. Attenuation is increased due to light escaping at cladding interface at angles greater than the critical angle at these bends.

Mass splicing
This is the simultaneous splicing of multiple fibres at one time. Currently mass splicing is done on ribbon cable, and the standard seems to be ribbon cable with 12 fibres. Special splice protectors are made for this purpose, as well as special equipment for splicing.

Matched cladding
Cladding with uniform refractive index.

Material Dispersion
The dispersion associated with a non-monochromatic light source due to the wavelength dependence of the refractive index of a material or of the light velocity in this material.

Modified chemical vapor deposition is a common used technology to produce preforms for optical fibres.

Mechanical splice
As opposed to a fusion splice. In a mechanical splice the fibres are glued or crimped into place, usually using a material in the form of a gel or liquid which matches the index of refraction.

Mode Field Diameter. The measure of the width of a guided optical power`s intensity in a single mode laser.

Micro-bending loss
Loss resulting from mechanical stress on a fibre which induces additional attenuation. In optical fibre, microscopic curvatures that create local axial displacements of a few micrometers and spatial wavelength displacements of a few millimeters. One frequent cause is longitudinal shrinking of the fibre buffer. But it can also result from poor drawing or cable manufacturing methods, installation, etc. Micro-bending causes transmission loss through a power-coupling effect from the guided modes to the radiation modes.

Mini Bundle Cable
Loose tube cable in which the buffer tube contains two or more fibers, typically 6 or 12 fibers.

Minimum bending radius
The smallest radius through which fibre can be bent before excessive light losses occurs. (For singlemode fibres)
the minimum bending radius is wavelength dependent.

MultiProtocol Label Switching; protocol to use Ethernet based structure e.g. for triple-play services

Multimode fibre.

Metal organic chemical vapor deposition is a common used technology to produce preforms for optical fibres.

Modal bandwidth
The bandwidth limiting characteristic of multi-mode fibre systems caused by the variable arrival times of various modes.

Modal Noise
Disturbance in multimode fibers fed by laser diodes. It occurs when the fibers contain elements with mode-dependent attenuation, such as imperfect splices, and is more severe the better the coherence of the laser light.

An electromagnetic field distribution that will propagate in a waveguide or will oscillate within a cavity, for instance a laser in the later case, and a optical fibre in the earlier case. Theoretically, modes are calculated mathematically in expressions that describe the propagation of light through a fibre.

Mode dispersion
Dispersion caused by differential path lengths in a multimode fibre.

Mode filter
An optical device that can select, attenuate, or reject a mode.

Multimode fibre
An optical fibre whose core is between 25 and 200 microns and capable of carrying several beams of light. Typical core diameters are 50µm, 62.5µm and 100µm. Said core is larger than a single mode fibre which can only carry one beam of light at a time, but can do so over long distances due to limits of modal dispersion

Multifibre cable
An optical fiber cable that contains two or more fibers.

Multimode laser
A laser that produces emissions in two or more transverse or longitudinal modes.

Multiplexing, optical
The combination of two or more wavelengths from two or more optical fibres onto a common optical fibre.

MUX (Multiplexer)
A device that combines two or more signals of different wavelengths onto a common optical fibre.

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