The optical fiber communication system is a communication system that uses light as the carrier wave, uses extremely high purity glass to draw a very thin optical fiber as the transmission medium, and transmits information with light through photoelectric conversion. Communication using optical fibers is called optical fiber communication.

Fiber optic transmission has many outstanding advantages:

1. Bandwidth: The width of the frequency band represents the size of the transmission capacity. The higher the frequency of the carrier, the larger the frequency bandwidth that can transmit the signal;

2. Low loss: When transmitting light of 1.31um, the loss per kilometer is below 0.35dB. If the light of 1.55um is transmitted, the loss per kilometer is smaller, which can reach below 0.2dB;

3. Light weight: The optical fiber is glass fiber with a small specific gravity, which makes it have the characteristics of small diameter and light weight, and the installation is very convenient;

4. Strong anti-interference ability: because the basic component of optical fiber is quartz, it only transmits light, does not conduct electricity, and is not affected by electromagnetic fields. The optical signal transmitted in it is not affected by electromagnetic fields. strong resistance;

5. High fidelity: Because optical fiber transmission generally does not require repeater amplification, it will not introduce new nonlinear distortion due to amplification. As long as the linearity of the laser is good, the TV signal can be transmitted with high fidelity;

6. Reliable working performance: The fiber optic system contains a small number of equipment (unlike the cable system that requires dozens of amplifiers), the reliability is naturally high, and the service life of the fiber optic equipment is very long, with a trouble-free working time of 500,000 ~750,000 hours;

7. Costs continue to decrease: As the source of materials (quartz) for making optical fibers is very rich, with the advancement of technology, the cost will be further reduced.

As a mainstream method of broadband access, optical fiber has the advantages of large communication capacity, long relay distance, good security performance, strong adaptability, small size and light weight, wide source of raw materials and low price. Applications are becoming more and more widespread.