nci's fiber facts

NCI'S FIBER FACTS

Buffer - Coating applied directly over core and cladding for strength and protection. Sizes range from 250µm to 900µm (µm = micron).

Cladding - A coating of material on the core of a lower refractive index than the core that causes reflection within the core so that

lightwaves can travel through the cable.

Core - The center of the fiber optic cable usually made of glass or plastic where the light is transmitted. Cores are either multimode

or singlemode.

Fiber Size - This consists of the core, cladding, and buffer sizes. A measure-ment of 62.5/125/900 means the core is 62.5µm, the cladding

is 125µm and the buffer coating is 900µm. Sometimes only the core and clad sizes are shown.

Fiber Types - There are 2 basic types:

Singlemode: Fiber optic cable designed to carry the single wavelength selected for transmission. Best used when clear transmission

for long distances is required. Typical diameter is 8m.

Multimode: Fiber optic cable designed to carry multiple signals set apart by frequency or phase. Best used where broadband

information-capacity is required. The core is much larger than singlemode fiber, usually 25 to 200 µm. The fiber core may

be either step index or graded index. Step index fiber has a uniform refractive index within the core and a sharp step-like

decrease in refractive index of the core and cladding. Graded index fiber has a core with many layers of glass each having

a lower index of refraction as you go outward from the axis. This reduces dispersion or fading of the transmission.

Micron (µm) - Unit of measurement equal to one millionth of a meter.