Optical fiber is the abbreviation of optical fiber, which is widely used in high-speed transmission communication field. In the early days, the most popular application of optical fiber was decorations made of optical fiber conduits. The structure of optical fiber can be simply divided into three parts, namely, core, cladding and sheath.

The conductor of optical fiber itself is mainly made of glass material (SiO2 _ 2), and its transmission is based on the principle that when light passes through a high refractive index medium and enters a low refractive index medium at an angle higher than the critical angle, it will produce total reflection, so that light can transmit in this medium while maintaining the characteristics of light waveform. The core part with high refractive index is the main channel of light transmission. The shell with low refractive index covers the whole core. Because the refractive index of the core is much higher than that of the shell, total reflection will occur, so light can be transmitted in the core. The purpose of the protective layer is mainly to protect the shell and core from damage, and also to increase the strength of the optical fiber.