The main body of fiber core data is silicon dioxide, which is doped with very little other data, such as germanium dioxide, phosphorus pentoxide, etc. The effect of doping is to improve the optical refractive index of data. Fiber core diameter is about 5~75 μ m。

Optical fiber has cladding on its surface, including one layer, two layers (inner cladding, outer cladding) or multiple layers (referred to as multi-layer layout), but the overall diameter is 100~200 μ M up and down. As for cladding materials, pure silicon dioxide is commonly used, and extremely small amounts of boron trioxide are also added. The latest method is to add a small amount of fluorine, that is, a small amount of silicon tetrafluoride is added to pure silicon dioxide. The effect of doping is the optical refractive index of low data. In this way, the refractive index of the fiber core is slightly higher than that of the cladding. The difference between the two seats ensures that the optical tension is limited to transmission in the fiber core.

The cladding surface shall also be coated with a coating, which can be made of silicon copper or acrylate. The effect of the coating is to protect the optical fiber from external damage and increase the mechanical strength of the optical fiber.

The outermost layer of the optical fiber is a jacket, which is a plastic pipe and also serves as a protective layer. Plastic pipes with different colors can also be used to distinguish different optical fibers.