Optical cable is composed of multiple optical fibers, with 6 cores, 40 cores... and many other specifications. Optical fiber is an abbreviation for optical fiber, which is composed of thin glass filaments with a diameter of about 0.1 mm. It is transparent and slender. Although it is thinner than a human hair, it has a waveguide structure that encloses light in it and propagates in the axial direction. It consists of a core with a higher refractive index and a cladding with a lower refractive index. To protect the optical fiber, the cladding is often covered with a layer of plastic for protection. The core diameter of the core is generally 50 or 62.5 μm, and the cladding diameter is generally 125 μm. Optical fiber communication is a communication method developed because of this magical structure of optical fiber, which uses light waves as the carrier frequency and optical fibers as the transmission medium.

Today, fiber optic cables have become an indispensable and important role in the field of information transmission and sensing. As a transmission medium, optical fiber communication has accounted for more than 80% of the world's communication business. Two hair-like optical fibers can transmit nearly 8,000 two-way telephone channels.

Compared with other transmission systems, the optical fiber information transmission system has a series of obvious advantages. First, the transmission frequency bandwidth is large and the communication capacity is large. Second, it has strong anti-interference and good confidentiality. Third, the signal attenuation is small and the relay distance is long. Fourth, the optical cable is light in weight and small in size. Fifth, raw materials are cheap. The raw material of optical fiber is mainly quartz, which accounts for about 14% of the total mineral deposits on the earth. Because optical fiber has the characteristics of integrating information transmission and sensing, it is convenient to realize online, real-time and dynamic monitoring and control of the target, and it has become the preferred material in artificial intelligence and neural network technology.

In mass production, fiber optic cables are much cheaper than cables that consume non-ferrous metals such as mid-coaxial. If there is no optical cable to form a huge number of long-distance circuits, it is unimaginable that long-distance calls can be made nationwide.