Advantages: 1. Large communication capacity and long transmission distance; the potential bandwidth of an optical fiber can reach 20THz. 2. Anti-electromagnetic interference and good transmission quality. Electrical communication cannot solve various electromagnetic interference problems. Only optical fiber communication is free from all kinds of electromagnetic interference. 3. The optical fiber is small in size and light in weight, making it easy to lay and transport; 4. The source of materials is abundant and the environment is well protected, which is conducive to saving non-ferrous metal copper. 5. No radiation, difficult to eavesdrop, because the light waves transmitted by optical fiber cannot escape outside the optical fiber. 6. Optical cables have strong adaptability and long life. Disadvantages: 1. Brittle texture and poor mechanical strength. 2. Cutting and splicing optical fibers requires certain tools, equipment and techniques. 3. Branching and coupling are inflexible. 4. The bending radius of the optical fiber cable cannot be too small (>20cm) 5. There is a problem of power supply difficulty.
Optical fiber communications technology stands out from optical communications and has become one of the main pillars of modern communications, playing a decisive role in modern telecommunications networks. As an emerging technology, optical fiber communication has developed rapidly and widely in recent years, which is rare in the history of communications. It is also an important symbol of the world's new technological revolution and the main transmission tool for various information in the future information society.
Fiber is the abbreviation of optical fiber. Optical fiber communication is a communication method that uses light waves as the information carrier and optical fiber as the transmission medium. In principle, the basic material elements that constitute optical fiber communication are optical fibers, light sources and light detectors. In addition to being classified according to manufacturing process, material composition and optical properties, optical fibers are often classified according to their uses in applications and can be divided into communication optical fibers and sensing optical fibers. The transmission medium optical fiber is divided into two types: general purpose and special purpose. Functional device optical fiber refers to the optical fiber used to complete the functions of amplification, shaping, frequency division, frequency doubling, modulation and optical oscillation of light waves, and is often used as a certain functional device. form appears.
Optical fiber communication is a communication method that uses light waves as carriers and optical fibers as transmission media to transmit information from one place to another. It is called "wired" optical communication. Today, optical fiber has become the main transmission method in world communications due to its transmission bandwidth, high anti-interference performance and small signal attenuation, which is far superior to cable and microwave communication transmission.
Before being received by the microcomputer system, the optical signal transmitted in the optical fiber must first be restored to the corresponding electrical signal. This conversion is achieved through an optical receiver. The function of the optical receiver is to convert the optical signal transmitted by the optical fiber into an electrical signal, and then deliver the electrical signal to the control system for processing. The optical receiver is based on the principle of the photoelectric effect, irradiating the PN junction of the semiconductor with light. The PN junction of the semiconductor will generate carriers after absorbing light energy, thus generating the photoelectric effect of the PN junction, thereby converting the optical signal into an electrical signal.
Semiconductor receivers used in optical fiber systems mainly include semiconductor photodiodes, phototransistors, photomultiplier tubes and photovoltaic cells. The phototransistor can not only convert the incident light signal into an electrical signal, but also amplify the electrical signal, thus matching well with the control system interface circuit, so the phototransistor is the most widely used.