What is optical fiber? Characteristics and classification of optical fiber

Optical fiber transmits signals in the form of light pulses, and uses glass or plexiglass as the network transmission medium. It consists of fiber core, cladding and protective cover. Optical fiber can be divided into Single Mode fiber and Multiple Mode fiber.

Single-mode optical fiber only provides one optical path, which is complicated to process, but has larger communication capacity and longer transmission distance. Multimode fiber uses multiple optical paths to transmit the same signal, and the transmission speed is controlled by the refraction of light.

Optical fiber is generally used for the transmission of communication networks. During the transmission process, different types of optical fibers are selected according to the environment and transmission requirements. There are the following types of optical fibers used in computer networks
A. 8.3pm core/125pm shell, single-mode optical cable;
B. 62.5um core/125um shell, multimode optical cable;
C. 5OPm core/125pm shell, multimode optical cable;
D. Loopm core/140pm shell, multimode optical cable.

The optical cable is mainly composed of optical fibers (glass hair as thin as hair) and plastic protective sleeves and plastic sheaths. There is no metal such as gold, silver, copper and aluminum in the optical cable, and there is generally no recycling value. An optical cable is a communication line in which a certain number of optical fibers form a cable core in a certain manner, which is covered with a sheath and some is also covered with an outer sheath to realize the transmission of optical signals. That is: a cable formed by optical fiber (optical transmission carrier) after a certain process. The basic structure of an optical cable is generally composed of a cable core, a reinforced steel wire, a filler, and a sheath. In addition, there are other components such as a waterproof layer, a buffer layer, and insulated metal wires as needed.

The main reason for the rapid development of fiber optic cable is that it has the following characteristics:
1. The transmission bandwidth is very wide and the communication capacity is very large;
2. Low transmission loss and long relay distance, especially suitable for long-distance transmission;
3. Strong anti-lightning and anti-electromagnetic interference capabilities;
4. Good confidentiality, not easy to be eavesdropped or intercepted data;
5. Small size and light weight;
6. Low bit error rate and high transmission reliability;
7. The price is falling continuously.

The basic structure of an optical cable is generally composed of a cable core, a reinforced steel wire, a filler, and a sheath. In addition, there are other components such as a waterproof layer, a buffer layer, and insulated metal wires as needed. The optical cable is composed of a reinforced core and a cable core, a sheath and an outer sheath. There are two types of cable core structure: single-core type and multi-core type: single-core type has two types: full type and tube bundle type; multi-core type has two types: ribbon and unit type. The outer sheath has two types of metal armor and non-armor.
The manufacturing process of the optical cable is generally divided into the following processes:
1. Screening of optical fiber: choose the optical fiber with excellent transmission characteristics and qualified tension.
2. Staining of optical fiber: Use standard full chromatogram to mark, requiring no fading and migration at high temperature.
3. Secondary extrusion: use plastic with high elastic modulus and low linear expansion coefficient to extruded into a tube of a certain size, put the fiber into the moisture-proof and waterproof gel, and store it for a few days (not less than two days) .
4. Twisted optical cable: twist several extruded optical fibers with the reinforced unit.
5. Squeeze the outer sheath of the optical cable: add a layer of sheath to the twisted optical cable.