Types of fiber optic cables
There are three types of commonly used fiber optic cables: single mode, multimode and plastic optical fiber (POF).
The fiber optic cable works as a light guide, guiding the light introduced from one side of the cable to the other side. The light source can be a light-emitting diode (LED) or a laser.
The light is turned on and off in a pulsed manner, and a light-sensitive receiver on the other side of the cable converts the pulses into the ones and digital zeros of the original signal.
Even laser light shining through a fiber optic cable is subject to loss of strength, mainly by the scattering of light, within the cable itself. Now a days many cable internet companies are available in market. The faster the laser fluctuates, the greater the risk of dispersion. Light enhancers, called repeaters, may be needed to refresh the signal in some applications.
While fiber optic cable has become cheaper over time (an equivalent length of copper cable costs less per meter but not in capacity) fiber optic connectors and the equipment needed to install it are still more expensive than their counterparts coppermade.
A single-mode cable is a single post (most applications use two fibers) of fiberglass with a diameter of 8.3 to 10 microns that only has one mode of transmission. The single-mode fiber has a relatively narrow diameter, by which only one mode typically propagates 1,310 or 1,550 nm. It charges more broadband than multimode fiber, but requires a light source with narrow spectral width. This type of fiber is used in many applications in which the data is sent in multi frequency so only one cable is needed (singlemode in a single fiber).
Singlemode fiber gives a higher transmission rate and up to 50 times more distance than a multimode, but it is also more expensive. Single-mode fiber has a much smaller core than multimode. The small core and the individual light wave virtually eliminate any distortion that may result from the overposition of light pulses, providing the lowest signal attenuation and the highest transmission speed of any type of fiber optic cable.
A multimode cable has a slightly larger diameter, with common diameters in the range of 50 to 100 microns for the component that charges the light. In most applications where the multimode cable is used, two fibers are required.
Multimode fiber provides high broadband with high speeds (from 10 to 100 MB) (in Gigabit distances of 275 m to 2 km are reached) over medium distances. Light waves are scattered in various ways, or modes, as they travel through the cable core typically 850 or 1,300 nm. The diameter of a typical multimode core can be between 50, 62.5, and 100 micrometers. Although, in long cables (more than 914.4 meters) multiple light paths can cause distortion on the receiver side, resulting in incomplete data transmission, so designers tend to use single-mode fiber in new applications that use Gigabit or more.
The use of fiber optics was generally not available until 1970 when Corning Glass Works managed to produce a fiber with a loss of 20 dB / km. It was recognized that optical fiber could be feasible for the transmission of telecommunications only if it was possible to develop such a pure glass that the attenuation was 20 dB / km or less. It means that 1% of the light would be lost after traveling 1 km. The attenuation of modern optical fiber varies from 0.5 dB / km to 1,000 dB / km depending on the optical fiber used. The attenuation limits are based on the application that you want to perform.
