Optical fiber uses optical pulses to transmit information along optical lines, instead of using electrical pulses to transmit information along cables. At one end of the system is the transmitter, which is the starting point of optical fiber line information. The coded electronic pulse information received by the transmitter comes from the copper cable, and then the information is processed and converted into equivalent coded optical pulses. Light-emitting diodes or injection lasers are used to generate light pulses, and lenses are used to concentrate the light pulses on the optical fiber medium, so that the light pulses can be transmitted in the optical fiber medium along the line. According to the principle of total internal reflection, the light pulse is easy to move in the optical fiber line, and the principle of total internal reflection in the optical fiber shows that when the incident angle exceeds the critical value, the light cannot overflow from the glass. Instead, the fiber will reflect back to the glass. Don't want to look at the above, look at this function: it enlarges the network transmission distance and regenerates the signal by retransmitting or forwarding the data signal (that is, amplifying and shaping the original signal). Principle: Repeater is a device connecting network lines, which is often used for two-way forwarding of physical signals between two network nodes. Repeater is the simplest network interconnection equipment, which mainly completes the function of physical layer, and is responsible for transmitting information bit by bit on the physical layer of two nodes, and completing the functions of signal replication, adjustment and amplification, thus prolonging the length of the network.