The principle that light travels in a curve was discovered many decades back. However, the technology to use this principle to our advantage is quite new and still developing. Using this principle the fiber optics technology to make cables has replaced the conventional copper wires. Due to fiber optics, we can now get improved quality of audio and video at a high speed.
In the year 1870, John Tyndall showed that light followed a curve of a stream of water which was poured from a container. This simple principle has led to the study and development of fiber optics. Later on, John Logie Baird patented a technique of transmitting light in a glass rod for use in an early color TV, but due to the optical losses inherent in the materials used at that time, it was impractical to use it. During the 1950s, more research and development into the transmission of visible images using optical fibers led to some success in the medical field, as they started using it for remote illumination and viewing instruments.
During the year 1966, George Hockham and Charles Kao proposed the transmission of information over glass fiber. They also realized that to make this a practical proposition, it was necessary to use much lower losses. This was the driving force which lead to developments to improve the previous optical losses in fiber manufacturing. Today, the optical losses are significantly lower than the original target laid by George Hockham and Charles Kao.
The fiber optics or optical fibers are long thin strands of very pure glass which have a diameter that of a human hair. These strands that are arranged in bundles are called optic cables, and used for transmitting light signals over long distances. When you look at a single optical fiber closely, you will observe there is a core, which is a thin glass center, then there is cladding which is the outer optical material surrounding the core, then there is a buffer coating which protects the fiber from damage and moisture.
There are two types of fiber optic cables, which are single-mode fibers and multi-mode fibers. Manufacturers consider size, attenuation, and bandwidth aspects for fiber optics specifications. While factors like concentricity of the core and cladding specifications do not affect you. The cable color code are followed using standard industry color codes. It is similar to the color code used for twisted pair cables, except that the second group of colors is used first and the new two colors are added at the end. For outdoor and burial types of cables, the jacket colors usually are black polyethylene for both the types of cables.
How Do They Work?
Light travels well through air or glass, but poorly through substances like wood or metal. Light moves at different speeds in different materials, it is fastest when moving through a vacuum. Thus the direction and speed of a light beam can be altered by measuring its index of refraction. Fiber optic cable is made from special materials, which has two important properties - light can travel easily through this medium; and the index of refraction of light is such that very little amount of light can escape. For communication purposes using fiber optic cables, a light source produces pulses of light that travel through this cable, these pulses carry info which can be later on translated into picture or sound.
They have revolutionized telecommunications. They are less expensive, but their installation can be expensive. Compared to copper wires, they are thinner and have higher carrying capacity. Also, there is less signal degradation. Unlike copper wires, in fiber optics there are light signals which are transferred from one fiber, that do not interfere with other fibers present in the same cable. They degrade very slowly. So, they can replace high voltage electrical transmitters, thus saving money. Fiber optics are ideal for carrying digital information, hence they are used especially when establishing LAN connections. They are lightweight and non-flammable and are so flexible, that they are used in many digital cameras too.
Due to so many advantages of these cables, they have replaced the conventional copper wires and are providing us with a better and faster transfer of picture and sound.