Fiber Optic :: Glossary :: G - I

Gap loss - The optical power loss caused by a space between axially aligned fiber optic cables. For waveguide-to-waveguide coupling, it is commonly called longitudinal offset loss.

GBPS - Giga Bits Per Second - 1 Billion Bits Per Second.

GHz. - Giga Hertz, 1 Billion Hz.

GI - Graded indexes.

GI-POF - Graded index plastic fiber optic cable.

GOF - Glass Optical Fiber.

Graded index fiber - A fiber optic cable where the core has a non-uniform index of refraction. The core is composed of concentric rings of glass where the refractive indices decrease from the center axis. The purpose is to reduce modal dispersion and thereby decrease fiber bandwidth.

Graded index profile - Any refractive index profile that varies with radius in the core.

GRIN - Graded indexes.

Ground loop noise - Noise that results when equipment is grounded at ground points having different potentials. This creates an unintended current path. The dielectric of fiber optic cables provides electrical isolation that eliminates ground loops.

Hard clad silica - A fiber optic cable with a hard plastic cladding surrounding a silica glass core.

Hertz - A unit of frequency equal to 1 cycle per second.

Hot plate - Heat source used to produce a mirror finish on the end of a plastic fiber optic cable.

HSPN - High Speed Plastic Network- a program funded by the US Government to promote plastic fiber optic cabling components and applications.

Hybrid adapter - Device that connects various connector types.

Hybrid cable - A cable composed of both a fiber optic cable and electrical conductors. Synonym for composite cable.

IDP - Integrated detector/amplifier.

IEC - International Electrical Commission.

IEEE - Institute of Electrical and Electronics Engineers.

Incident angle - The angle between an incident ray and a line perpendicular to an optical surface.

Index matching material - A material used at an optical interconnection. It has a refractive index close to that of the fiber optic cable core and is used to reduce Fresnel reflections.

Index of refraction - The ratio of the speed of light in a vacuum to the speed of light in a material. The symbol for it is 'n'.

Index profile - A graded-index fiber optic cable. In it the refractive index at a point varies with the distance of the point from the cylindrical axis i.e. n varies with the radius.

Infrared - The designation for electromagnetic waves at wavelengths between the visible part of the spectrum (approximately 750 nm) and the microwave band (approximately 30 mm).

ILD - Injection Laser Diode.

Insertion loss - The loss in the power of a signal that results from inserting a passive component into a previously continuous path. Examples of such passive devices are connectors, inline star couplers and splices.

Integrated detector/amplifier - A detector package containing a pin photodiode and a transimpedence amplifier.

Interface - The debarkation point or location on a data device where data comes out of or goes into the device. Examples are the RS-232 interface and the Mouse-PC interface.

Intrinsic losses - Loss caused by fiber optic cable parameter mismatches when 2 non-identical cables are joined. Examples of such parameters are core dimensions and index profiles.

IR - Infrared.

ISDN - Integrated Services Digital Network. A TELCO offering to allow computers to communicate through the telephone Wide Area Network at speeds up to 128 KBPS.

ISO - International Standards Organization. This is an independent international body formed to define standards for multi-vendor network communications. Its 7 layer Open Systems (OSI) reference model defines the protocol layers of network architectures which vendors should account for in their product offerings.

Isolation - Also referred to as far end crosstalk or far end isolation. Predominantly used in reference to WDM products. It is a measure of light at an undesired wavelength at any given port.