There are 2 major kinds of optical fibers: plastic optical fibers (POF) and glass optical fibers – so how are optical fibers made?
1. Materials for optical fibers
Plastic optical fibers are often made for lighting or decoration like Optical Fiber Coloring Machine. They are also used on short range communication applications including on vehicles and ships. Because of plastic optical fiber’s high attenuation, they have restricted information carrying bandwidth.
Whenever we discuss fiber optic networks and fiber optic telecommunications, we actually mean glass optical fibers. Glass optical fibers are generally created from fused silica (90% at the very least). Other glass materials such as fluorozirconate and fluoroaluminate will also be utilized in some specialty fibers.
2. Glass optical fiber manufacturing process
Before we start talking the best way to manufacture glass optical fibers, let’s first check out its cross section structure. Optical fiber cross section is really a circular structure made from three layers inside out.
A. The interior layer is referred to as the core. This layer guides the light preventing light from escaping out with a phenomenon called total internal reflection. The core’s diameter is 9um for single mode fibers and 50um or 62.5um for multimode fibers.
B. The center layer is known as the cladding. It has 1% lower refractive index than the core material. This difference plays a vital part overall internal reflection phenomenon. The cladding’s diameter is usually 125um.
C. The outer layer is known as the coating. It is actually epoxy cured by ultraviolet light. This layer provides mechanical protection for your fiber and definitely makes the fiber flexible for handling. Without this coating layer, the fiber will be really fragile as well as simple to break.
Because of optical fiber’s extreme tiny size, it is not practical to create it in a single step. Three steps are needed as we explain below.
1. Preparing the fiber preform
Standard optical fibers are created by first constructing a sizable-diameter preform, with a carefully controlled refractive index profile. Only several countries including US are able to make large volume, top quality Optical Fiber Ribbon Machine preforms.
This process to create glass preform is known as MOCVD (modified chemical vapor deposition).
In MCVD, a 40cm long hollow quartz tube is fixed horizontally and rotated slowly on the special lathe. Oxygen is bubbled through solutions of silicon chloride (SiCl4), germanium chloride (GeCl4) and/or other chemicals. This precisely mixed gas will then be injected into the hollow tube.
Since the lathe turns, a hydrogen burner torch is moved up and down the away from the tube. The gases are heated up from the torch up to 1900 kelvins. This extreme heat causes two chemical reactions to happen.
A. The silicon and germanium react with oxygen, forming silicon dioxide (SiO2) and germanium dioxide (GeO2).
B. The silicon dioxide and germanium dioxide deposit on the inside of the tube and fuse together to make glass.
The hydrogen burner is then traversed up and down the size of the tube to deposit the fabric evenly. Following the torch has reached the conclusion from the tube, this will make it brought back to the starting of the tube and also the deposited particles are then melted to form a solid layer. This process is repeated until a sufficient quantity of material has become deposited.
2. Drawing fibers on the drawing tower.
The preform is then mounted towards the top of a vertical fiber drawing tower. The preforms is first lowered in to a 2000 degrees Celsius furnace. Its tip gets melted until a molten glob falls down by gravity. The glob cools and forms a thread since it drops down.
This starting strand will be pulled through a series of buffer coating cups and UV light curing ovens, finally onto a motor controlled cylindrical fiber spool. The motor slowly draws the fiber from your heated preform. The ltxsmu fiber diameter is precisely controlled by a laser micrometer. The running speed in the fiber drawing motor is all about 15 meters/second. As much as 20km of continuous fibers can be wound onto one particular spool.
3. Testing finished optical fibers
Telecommunication applications require very good quality glass optical fibers. The fiber’s mechanical and optical properties are then checked.
A. Tensile strength: Fiber must withstand 100,000 (lb/square inch) tension
B. Fiber geometry: Checks FTTH Cable Production Line core, cladding and coating sizes
A. Refractive index profile: By far the most critical optical spec for fiber’s information carrying bandwidth
B. Attenuation: Very critical for long distance fiber optic links
C. Chromatic dispersion: Becomes increasingly more critical in high-speed fiber optic telecommunication applications.