5-2
Glossary, cont.
Detector. An optoelectronic transducer used in fiber optics for converting optical power to electric current. In
fiber optics, usually a photodiode.
Diffraction. The bending of radio, sound, or light waves around an object, barrier, or aperture edge.
Dispersion. A general term for those phenomena that cause a broadening or spreading of light as it
propagates through and optical fiber. the three types are modal, material, and waveguide.
Entrance Facility. An entrance to a building for both public and private network service cables including the
entrance point at the building wall and continuing to the entrance room or space.
Equilibrium Mode Distribution (EMD). The steady modal state of a multimode fiber in which the relative power
distribution among modes is independent of fiber length.
Equipment Room. A centralized space for telecommunications equipment that serves the occupants of the
building. Equipment housed herein is considered distinct from a telecommunications closet because of its
nature or complexity of the equipment.
Frequency. Of a periodic wave, the number of identical cycles per second. Usually expressed in Hertz.
Fresnel Reflection. The reflection that occurs at the planar junction of two materials having different refractive
indices; Fresnel reflection is not a function of the angle of incidence.
Graded-index Fiber. An optical fiber whose core has a nonuniform index of refraction. The core is composed
of concentric rings of glass whose refractive indices decrease from the center axis. The purpose is to reduce
modal dispersion and thereby increase fiber bandwidth.
Generic Cabling Standard. A cabling standard that calculates link budgets based on the passive component
configuration of the network, and is protocol-independent. Examples are TIA/EIA-568 and ISO 11801.
Horizontal Cross-Connect (HC). A cross-connect of horizontal cabling to other cabling, e.g., horizontal,
backbone, equipment.
Index of Refraction. The ration of the velocity of light in free space to the velocity of light in a given material.
Insertion Loss. The loss of power that results from inserting a component, such as a connector or splice, into
a previously continuous path.
Interconnection. A connection scheme that provides for the direct connection of a cable to another cable or to
an equipment cable without a patch cord or jumper.
Intermediate Cross-Connect (IC). A cross-connect between the main cross-connect and the horizontal
cross-connect in backbone cabling.
Laser. Light Amplification by Stimulated Emission of Radiation. A light source producing, through stimulated
emission, coherent, near monochromatic light. Lasers in fiber optics are usually solid-state semiconductor
types.
Appendices
UNIT 5
