Optical fiber is the shorthand of optical fiber. It is a fiber made of glass or plastic, which can be used as a light conduction tool. The principle of transmission is' total reflection 'of light.
Optical fiber communication system is a communication system that uses light as carrier and uses extremely high purity glass to produce fine optical fiber as transmission medium, and transmit information through light and light. Communication using optical fiber is called optical fiber communication.
Fiber transmission has many outstanding advantages:
1. Bandwidth: the width of the band represents the size of the transmission capacity. The higher the frequency of the carrier, the greater the bandwidth of the signal can be transmitted.
2, low loss: transmission of 1.31um light, the loss of 0.35dB per kilometer below the transmission of 1.55um light, less loss per kilometre, up to less than 0.2dB;
3, light weight: fiber is glass fiber, small proportion, make it with small diameter, light weight, installation is very convenient;
4, the anti-interference ability is strong: because the basic component of optical fiber is quartz, which only passes light and does not conduct electricity, and is not affected by electromagnetic field. The optical signal transmitted in it is not affected by electromagnetic field, so optical fiber transmission has strong resistance to electromagnetic interference and industrial interference.
5, high fidelity: because fiber transmission generally does not need relay amplification, it does not cause new nonlinear distortion because of amplification. As long as the linearity of the laser is good, the TV signal can be transmitted high and true.
6, reliable performance: optical fiber system contains a small number of devices (unlike dozens of amplifiers in cable system), and the reliability is also high. With the life of optical fiber equipment is very long, the trouble free working time is 500 thousand to 750 thousand hours.
7, the cost continues to decline: as the materials (quartz) made of fiber are very rich, the cost will be further reduced as the technology progresses.
As a mainstream way of broadband access, optical fiber has the advantages of large communication capacity, long distance relay, good secrecy performance, strong adaptability, small volume and light weight, raw material source and wide price. Therefore, the application of optical fiber in communication system is more and more extensive.
Common fiber specifications are:
Single mode: 8/125 mu m, 9/125 mu m, 10/125 mu m
Multimode: 50/125 mu m, (European standard)
62.5/125 mu m, (American Standard)
At present, the optical fiber used in the optical fiber communication system includes quartz fiber, plastic package fiber, single mode fiber and multi mode fiber.