What is fiber optics? Types of fiber optic cables

What is fiber optics?

We are used to the idea that information travels in different ways. When we talk on the landline, a metal cable takes the sounds of our voice to an outlet, where another cable takes it to the local telephone exchange. Mobile phones work differently: they send and receive information using invisible radio waves, a technology called wireless because it does not use cables. Fiber optic works in a third way. Send coded information in a beam of light along a glass or plastic tube. It was originally developed for endoscopes in the 1950s to help doctors see the inside of the human body without having to open it first. In the 1960s, engineers found ways to use the same technology to transmit calls at the speed of light (usually 186,000 miles or 300,000 km per second in a vacuum, but reduce this speed by approximately two-thirds on a fiber cable optics)

Types of fiber optic cables.

Optical fibers carry light signals in what are called modes. It seems technical, but it only means different ways of traveling: one way is simply the path that follows a ray of light along the fiber. One way is to go directly to the center of the fiber. Another is to bounce the fiber at a low angle. Other modalities provide for the rebound of the fiber in other angles, more or less steep.

The simplest type of fiber optic is called single mode. It has a very thin core of about 5-10 microns (millionths of a meter) in diameter. In a single-mode fiber, all signals travel directly through the medium without bouncing off the edges (yellow line in the diagram). Cable television, Internet and telephone signals are generally carried by single-mode fibers, wrapped in a large package. Cables like this can send information for over 100 km (60 miles).

Another type of fiber optic cable is called multimode. Each optical fiber in a multimode cable is approximately 10 times larger than one in a single-mode cable. This means that light rays can travel through the nucleus following a variety of different paths (yellow, orange, blue and cyan lines), in other words, in different ways. Multimode cables can only send information at relatively short distances and are used (among other things) to connect computer networks.

Even thicker fibers are used in a medical instrument called a gastroscope (a type of endoscope), which doctors touch someone's throat to detect diseases inside the stomach. A gastroscope is a fiber optic cable often made up of many optical fibers. At the upper end of a gastroscope, there is an eyepiece and a lamp. The lamp illuminates its light through a part of the cable towards the patient's stomach. When light reaches the stomach, it is reflected into the walls of the stomach in a lens at the bottom of the cord. Then, lift another part of the cable into the doctor's eyepiece. Other types of endoscopes work the same way and can be used to inspect different parts of the body. There is also an industrial version of the instrument, called a fiberscope, which can be used to examine things like inaccessible pieces of machinery in aircraft engines.

Read Also : cable installer certifications