Chinese English
Chinese English
No matter in the past or in the future, we always need more, faster, clearer and accurate information. Thousands of years ago, we Chinese had used light to realize the rapid spread of information. By burning combustibles such as straws and using fireworks to report the enemy's situation, we could make the next post more vigilant. Now, although we have built various forms of communication networks in the water, high-rise buildings, space and underground, the best way is still optical communication. The wave separation system is indispensable for a large-capacity network.
Light can not only bring light, but also be used to spread information. The propagation speed of light in the air is about 300 thousand kilometers per second, and that in optical fiber is about 200 thousand kilometers per second, therefore, optical fiber is the best carrier to realize information dissemination. Optical Fiber Communication can realize the rapid transmission of data, voice, video and other information, while WDM technology can increase the transmission rate dozens of times, then how does WDM achieve this?
According to the basic characteristics of light, when a beam of white light passes through a triangular prism, it can be divided into seven colors of light, and the light of these seven colors will be synthesized into a beam of white light after passing through a triangular prism, according to this optical phenomenon, we can know that light can be further subdivided. Even the light of the same color can be subdivided. We all know that light is a kind of electromagnetic wave, so it has wave length and frequency. Usually we use wavelength and frequency to represent a certain segment of light wave.
The light in the optical fiber is composed of multiple wavelength, and we find that each wavelength can carry different information independently, so as to realize more information than one light transmission. That is to say, if a wavelength component contains 80 wavelength, its information transmitted is 80 times of that of a single wavelength. For the convenience of understanding, we can use traffic system to compare with WDM system:
1. The signal light of one road is equivalent to the running of one bicycle lane and one vehicle. WDM system is that after the number of lanes is enlarged by 80 times, 80 vehicles operate at the same time, realizing the expansion of optical channel.
2. If each vehicle transports 1 ton to 10 tons, the carrying capacity will be greatly increased. Each wavelength transmits 1G, increasing to Shan Bo 10G/25G/40G/100G, then the maximum transmission of 80 channels is 8 T, which greatly improves the requirement of transmission rate and large bandwidth.
3. For example, common communication technologies such as SDH, routers and switches need to add the same equipment to continue the next stage of transmission after a certain distance of transmission, such as 80km and 100 km, just like a car driving 100km needs to be changed to the next stage, the cost is very high. However, WDM system can fuel the cars at regular intervals and amplify the signal, which can continuously transmit thousands of kilometers without changing cars, and can save a lot of costs at the same time.
