Application of optical fiber in the field of communication transmission
Since the famous Chinese physicist Dr. Charles Kao put forward the "theory of optical transmission", the practical optical fiber transmission products began in 1976 and went through the development process of PDH→SDH→DWDM→ASON→MSTP.
At the beginning of this century, ASON/OADM technology has been widely used in communication technology and gradually developed into ROADM technology with backbone network transmission as the medium.
Characteristics of optical communication technology
Large information capacity
Fiber optic communication has high capacity, and the transmission width of fiber is much wider than the width of cable or copper wire.
In theory, a single fiber the thickness of a human hair could carry 100 billion channels simultaneously.
Although it has not reached such a high transmission capacity, the experiment of simultaneously transmitting 240,000 channels with a single optical fiber has been successful, which is dozens or even thousands of times higher than the traditional open wire, coaxial cable, microwave, etc.
The transmission capacity of an optical fiber is so huge, and a fiber optic cable can include dozens or even thousands of optical fibers, if coupled with WDM technology to use a fiber as several or dozens of optical fibers, the communication capacity is even more amazing.
Low loss, long distance transmission
The loss rate of optical fiber communication is much lower than that of ordinary communication. Because the optical fiber has a very low loss coefficient (the commercial quartz fiber has reached below 0.19dB/km), if matched with appropriate optical transmission and optical receiving equipment, the relay distance can reach more than hundreds of kilometers.
This is the traditional cable (1.5km), microwave (50km) and other simply can not be compared to it.
Therefore, optical fiber communication is especially suitable for long-distance primary and secondary trunk communication.
It is reported that the experiment of using a single optical fiber to simultaneously transmit 240,000 telephone lines and 100 kilometers without relay has been successful.
In addition, the experiment of optical soliton communication has reached the level of transmission of 1.2 million telephone channels and 6000 kilometers without relay.
Optical fiber not only has low loss, but also can carry out long-distance communication. At present, the longest communication distance can reach more than ten thousand meters. Therefore, optical fiber communication is more practical for the place where the information of social network is compared.
Moreover, fiber optic communication has high cost performance and good security.
Strong ability to resist electromagnetic interference
Optical fiber is mainly made of quartz as a raw material to insulate material, this material insulation is good, and not easy to be corroded.
The most important characteristic of optical fiber communication is the ability to resist electromagnetic interference, and is not affected by the natural sunspot activity interference, ionospheric changes and lightning interference, also will not be affected by artificial electromagnetic interference.
And optical fiber communication can also be compounded with the power conductor to form a compound type of optical cable or set up in parallel with the high voltage wires. This characteristic of optical fiber communication has a great effect on the communication system in the field of strong electricity.
Optical intensity communications, which can be protected from the benefits of electromagnetic pulses, can also be used in military applications.
Good security performance and confidentiality
In the transmission of radio waves in the past, because of the electromagnetic wave in the transmission process of leakage phenomenon, it will cause the interference of various transmission systems, and the confidentiality is not good.
However, optical fiber communication mainly uses light waves to transmit signals. The light signals are completely limited in the structure of optical waveguide, while other leaked rays will be absorbed by the envelope outside the optical fiber line. Even in the ring with bad conditions or at the corner, there is rarely the phenomenon of light wave leakage.
And in the process of optical fiber communication, can make a lot of optical fiber lines into a cable, also will not interfere with the situation.
Therefore, optical fiber communication has strong anti-interference ability and confidentiality, and the security performance of optical fiber communication is also very high.
Light weight, small volume, convenient for construction and maintenance
Its tensile strength is good, the quality is small, and relatively small, so the cable can maximize the utilization rate of the wiring pipeline, and can reduce the installation problems as far as possible.
According to the following figures, the advantages of optical fiber can be analyzed. 1000 twisted-pair wires with a length of 1km weigh 8000kg, while the two fibers with a larger capacity of 1km weigh only 100kg. This greatly reduces the need for expensive mechanical support systems that must be maintained, so optical fiber outperforms copper wire.
Easy for construction maintenance Easy for construction maintenance.
The laying method of optical fiber and cable is convenient and flexible. It can be buried directly, laid in pipelines, or laid underwater or overhead.
Raw materials are plentiful and potentially cheap
The most basic raw material for making quartz fiber is silica, that is, sand, which is almost inexhaustible in nature.So the underlying price is very low.