What are the Different Types of Fiber-Optic Cable?

There are three types of fiber-optic cable typically used: single-mode, multi-mode and plastic optical fiber (POF). The type of cable used depends on its usage. Multi-mode and single-mode are used in fiber-optic networks to transmit data. POF cables are generally not used to transmit data but instead are used for aesthetic purposes, such as in toys and decorative displays.

Fiber-optic cables, irrespective of their use, are created in similar ways. Two layers of glass or plastic are melted together to form the core and the cladding; the cladding is the outer layer. This structure is then extended out to create a long, very thin fiber. The fibers are then cooled and put into spools. They are bundled together to create fiber-optic cables with an extra coating, called a jacket, around them for protection.

The different types of fiber-optic cable vary in consistency and size, but most are thinner than a human hair. In the case of multi-mode and single-mode cables, the glass used to make them is very pure, as the refractive properties have to be high standard in order to conduct a data signal — in this case made of light — through a network. Plastic cables are not made from such high-quality material, so are much cheaper to buy and make; they also are thicker in diameter.

Single-mode fiber-optic cables have a thin core; they only allow for one data mode, unlike multi-mode, which can utilize several different modes. The single-mode cables provide a higher transmission rate and can carry a signal 50 times farther than multi-mode, but they are also more expensive. The narrower core in single-mode cable, and its use of a single light wave, provides the least signal attenuation and highest speeds among the different types of fiber-optic cable available. Its biggest disadvantages are that it needs a light source with a narrow spectral range, and it can only use one mode of transmission.

Multi-mode fiber-optic cables have a thicker core than single-mode. They can carry data that has been encoded using multiple light sources; this allows for multiple signals to be sent on one cable. Multi-mode fibers provide high bandwidth at high speeds over short to medium distances. The disadvantage of multi-mode cable is that because of the multiple data streams, the signal dissipates over longer distances, resulting in an incomplete and imprecise transmission of data.

Plastic optic fibers do not typically have the purity to transmit the signals required for larger fiber-optic networks, but can be used in small networks with transmission distances of less than a 100 feet. Since the late 1990s, their use in networks has been slowly growing. They are more commonly used in toys or decorative displays that produce light signals, however. An example of this is an electronic reproduction of a vase of flowers, wherein the flowers are replaced by optical fibers. POF is the cheapest to make among the different types of fiber-optic cable.