Pure glass wires, thin - like human hair - carry digital information over long distances. Fiber-optic installation
We mentioned that optical fiber is a thin, long wire of pure glass that is arranged in packages called Optical Cables for use in the transmission of optical signals over large distances. If we take a closer look at one of the fiber optics, we'll see that it consists of the following parts:
- 1- Heart or core: it is the center of the tissue (fiber) through which light travels.
- 2- Cladding: The outer material of the tissue that surrounds the heart and its mission is to reflect and return the light coming out of the heart.
- 3- Buffer Coating: It is a plastic cover, and its mission is to protect the light fabric from damage and moisture. Hundreds of thousands of these optical fibers are arranged in light cable-shaped packages. These packages are protected by the outer shell of the cable called jacket.
Fiber optics are divided into two main types
- 1. Single-Mode Fiber. It has a small heart with a diameter of 9 microns, and transmits infrared laser signals with a wavelength ranging from 1,300 to 1,550 nm.
- 2. Multi-Mode Fiber.
This has a larger diameter of 62.5 microns, and carries and transmits infrared signals ranging in diameter from 850 to 1,300 nm from light Emitting Diodes LED. Some fibers can be made of plastic, but the core part has a relatively large diameter (1 mm), and is suitable for transmitting light that can only be seen and whose wavelength is greater than 650 nm, which is the light emitted by the electronic valve (LED) and this type of fiber is not suitable for the transmission of laser light (emitted from the laser launcher). Here we can wonder how these fibers can transmit light and digital information.
How fiber optics work:
Let's say we want to send beams of light across a path, so we can direct the light across that path as the light goes through straight lines. The problem we can encounter is if this path has a turning point, what do you work in such a situation? The solution is to place a mirror at that bending point to reflect the light at this angle and return it to the path. How if the path has many turning points? In this case we need a mirror at each turn, and the mirror is placed at a certain angle to allow the light to be returned to the heart at every angle along the path. That's exactly what's happening inside the fiber optics. Light travels through the core (path) with regular jumps from the casing (mirror) at the turning points according to the so-called Total Internal Reflection, and because the casing does not absorb any of the mobile light signals within the heart, the light signals can travel long distances. However, some of these signals are weakened within the fibers due to the inpurity and contamination of the glass, for example, the extent to which these signals can be weakened depends on the degree of purity of the glass from which the fiber is made, and also depends on the wavelength of the light transmitted (e.g. 850 nm weakens by 60 to 75 percent per kilometer) and some fibers weaken the signal by less (10 percent per kilometer at 1550 nm wavelength).
The fiber optic communication system consists of the following elements:
Transmitter: Receives and directs the light-source device (LASER or LED) and turns it on and off in the correct sequence, thus generating the light signal. The transmitter is close to the optical fiber and may contain focused lenses to collect and focus light into the optical fabric. Laser light has more power than light from the emitter valve but is more sensitive to temperature change, and it is more expensive. Fiber Optics is the communication environment between the transmitter and the receiver. Optical Regenerator: We have previously indicated that there has been some loss of signal (Signal Loss) when light within the fiber travels over long distances — as in submarine cables — and therefore connects boosters and signal regeneraters along the cable, to enhance weak signals. This device consists of fiber optics with special coverage inlaid (doping), and this section of fiber works as a laser pump; This means that this device acts as if it were a laser amplifier for the next signal to it. Optical Receiver: Takes, decrypts, decrypts and sends it as an electrical signal to the user, whether it's a computer, cable TV or a phone. The photo receiver contains photocells or photodiode synosis to sense and notice the light signal. Why has fiber optic technology revolutionized the world of communications compared to other conventional wires - copper wires, for example?
The reason appears in the following points:
- 1. Relatively low cost.
- 2. Fiber paper and accuracy. And that leads to.
- - High carrying capacity due to fiber sheeting, many of them can be packed inside a cable with a certain diameter than if copper wires in a cable have the same diameter, which means more connected telephone lines or TV channels available if we are talking about cable TV system.
- - It has less signal.
- - Carries light signals. Unlike copper wires with electrical signals, interference signals do not interfere with each other, which means clearer phone calls or television reception.
- - Lower Power transmission capacity. - Digital Signal. Fiber optics are mainly designed to transmit digital signals, and these are especially useful in computer networks or the Internet.
- - Non-flammable. Due to the lack of electrical current in it, there is no risk of burning. - Lighter (lightweight). compared to copper wire. It occupies less space when passed underground.
- - Flexible. Because of its high flexibility, transmission and reception of light, it is used in many digital cameras for medical imaging purposes, examination and operation of welding inside pipes and engines that are difficult to access in aircraft, cars and rockets, as well as in the plumbing and examination of narrow pipes.
- How do you make fiber optics? We have already mentioned that the main material in its manufacture is glass, for which sand is the main source, because of the many details in this subject that we will mention in short. The fiber optic industry requires passage in several stages:
- Initially, a glass cylinder was made by modified chemical vapor Deposition, a complex process that takes place under high temperature and special chemical conditions, in which sicl4 and Gecl4 chloride interact with oxygen bubbles, to produce sio2 silicon oxide and Geo2, which are combined and dissolved into the tubes to form glass or fiber material. They are then pulled into thin and long wires in lathe-like machines and are very special and precise, called fiber drawing towers and the fiber is covered with a layer of plastic to protect it. The optical fiber is then examined in several aspects such as: tensile strength, cardiac diameter and dimensions of protective casings, the extent of signal weakness with increased length, beam width (bandwidth), operating temperature and humidity and their connection to low signal, and finally underwater conductivity.