In the field of optical fiber commu

In the field of optical fiber communication, the ultimate pursuit of scientific researchers is to make the transmission bandwidth larger, the transmission distance longer and the acceptance sensitivity higher. In recent years, the application of these communication technologies, such as the popularity of video conference and Internet, and the information growth rate they generate are explosive, which requires higher and higher transmission performance of communication system, especially its physical layer, because the physical layer is the foundation of the whole communication system. Therefore, WDM technology can not meet the requirements of optical fiber communication system for system bandwidth and transmission distance. Although EDFA is also applied, it still can not meet the requirements of optical fiber communication researchers. Therefore, the traditional optical fiber communication technology has not been able to meet the requirements of communication, which is inevitably replaced by more promising and advanced communication technology. However, with the rapid development of optical fiber communication technology, the emergence of new technology is bound to require new equipment, which is inevitable. However, the price of optical devices has always been high, so if large-scale replacement of communication equipment, it needs a lot of cost, so operators can not accept it. Therefore, for manufacturers of equipment, the risk of research and development of new optical fiber communication technology is also great, which requires us to study how to improve the performance of optical fiber communication system on the basis of existing equipment Yes, coherent optical communication system came into being in such a background.