When light from a source is sent through a fiber optic cable, the light wave wave both bounces around inside the cable and passes through the cable to the outer protective jacket. When a light signal inside the cable bounces off the cable wall and back into the cable, this is called reflection. When a light signal passes form the core of the cable into the surrounding material, this is called refraction.

Light can be transmitted through a fiber optic cable using two basic technique, called single-mode transmission, requires the use of a very thin fiber optic cable and a very focused light source, such as a laser. When a laser is fred down a narrow fiber, the light follows a tight beam, and so there is less tendency for the light wave to reflect. Thus, this technique allows for a very fast signal with little signal degradation (and thus less noise) over long distances. Because lasers are used as the light source.single-mode transmission is a more expensive technique than the second fiber optic cable signaling technique. Any application that invdvers a large amount of data transmitted at high speeds is a candidate for signal-mode transmission.

The second signaling technique, called multimode transmission, use a slightly thicker fiber cable and unfocused light source, such as an LED. Because the light source is unfocused, the light wave experiences more refraction and reflection as it propagates through the wire. This noise results in signals that cannot travel as far or as fast as the signals generated with the single-mode technique. Correspondingly, multimode transmission is less expensive than single-mode transmission. Local area networks that employ fiber optic cables often use multimode transmission.

Single-mode and multimode transmission techniques use fiber optic cable with different characteristics. The core of single-mode fiber optic cable is 8.3 microns wide, and the material surrounding the fiber, the cladding, is 125 microns wide. Hence, single-mode fiber optic cable is labeled 8.3/125 (described as 9/125 in Fiberstore) cable. The core of multimode fiber optic cable is most commonly 62.5 microns wide, and the cladding is 125 microns. Multimode fiber optic cable is labeled 62.5/125 (OM2) cable. Outer sizes of multimode fiber optic cable include 50/125 (OM1) and 100/140 microns.

About the Author:

Fiberstore is a largest fiber optic cable supplier in China, who provides bulk fiber optic cable and sales for fiber patch cords.