![]() The entire preform manufacturing process is highly automated with minimal human involvement. At the end of this process, an operator separates the preform from the rest of the glass assembly and moves it to the next step. All critical process parameters are monitored and controlled in real time by on-line computers that are also programmed to collect all pertinent process data.Īfter the desired amount of core material is deposited the chemical flow is eliminated, the speed of the torch is decreased and the temperature of the flame is increased so that the tube collapses into a solid rod. For example, mass flow controllers are used to meter chemicals for the reaction. The precise delivery of chemicals is ensured through the design of manufacturing equipment that performs accurately and consistently. This, in conjunction with the ability to change the speed at which the burner moves and the temperature of the flame, gives us the ability to manufacture a wide range of ultra-pure optical fiber types. For every sweep of the burner, the manufacturer can modify the composition, viscosity and thickness of the deposited layer in order to produce specific fiber designs. ![]() The process is repeated for many hours as each subsequent core layer is formed. 2 for a schematic diagram of the process.) The deposited material will form the core region of the optical fiber( see Fig. As the burner traverses over the deposited soot, the heat transforms these solid white particles into pure, transparent glass, in a process called vitrification. Once the soot is formed, it is deposited on the inner wall of the tube. As the gasses flow inside the tube, they react to the heat by forming solid submicron particles, called "soot," in the vicinity of the heat zone. The pure silica tube is mounted on a lathe equipped with a special heat torch. In the Modified Chemical Vapor Deposition (MCVD) process, the highly controlled mixture of chemicals described above is passed through the inside of a rotating glass tube made of pure synthetic SiO2. There are several methods used to manufacture preforms. Also, the core composition and the refractive index of graded-index multimode fibers changes across the core of the fiber to give the refractive index a parabolic shape. Multimode fibers typically have a much higher refractive index, and therefore much higher germania content. Single-mode fibers typically have only small amounts of germania and have a uniform composition within the core. The core composition of all standard communication fibers consists primarily of silica, with varying amounts of germania added to increase the fiber's refractive index to the desired level. GeCl4 (gas) + O2 > GeO2 (solid) + 2Cl2 (in the presence of heat) SiCl4 (gas) + O2 > SiO2 (solid) + 2Cl2 (in the presence of heat) The basic chemical reaction of manufacturing optical glass is: These chemicals are used in varying proportions to fabricate the core regions for the different types of preforms. Ultra-pure chemicals - primarily silicon tetrachloride (SiCl4) and germanium tetrachloride (GeCl4) - are converted into glass during preform manufacturing. The first step in manufacturing glass optical fibers is to make a solid glass rod, known as a preform. manufacturing of the pure glass preform and 2. There are two main steps in the process of converting raw materials into optical fiber ready to be shipped:ġ. Using a graded index core, where layers of light have lower index of refraction as you go further from the center of the core, minimizes dispersion but complicates the manufacturing process. With its relatively large core, multimode fiber suffers more dispersion than singlemode. Therefore, multimode fiber propagates more than one mode of light. Multimode fiber has a large core diameter compared to the wavelength of the transmitted light 50 or 62.5 microns. ![]() The small core size limits the transmitted light in the fiber to only one principle mode, which minimizes dispersion of light pulses, increasing the distance the signal can be sent. Single-mode fiber has a smaller core - only 9 microns in diameter - and only 6 times the wavelength of light it transmits. ![]() Both types of fiber are composed of only two basic concentric glass structures: the core, which carries the light signals, and the cladding, which traps the light in the core (Fig. Some basic facts about how optical fiber is manufactured may help to provide a better understanding of how optical fiber works too.Īs you know, there are two main types of optical fiber: single-mode and multimode. It's certainly not obvious how something only 1/8 of a mm - 0.005 inches - in diameter can be made with such precison. ![]() The Fiber Optic Association - Tech Topics ![]()
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