Research On Phase Stablization In Coherent Millimeter-Wave Microwave Photonic Link

With the speedy development of global informatization, the trend of communication industry is towards portability, wireless, digitalization and broadband network. As wireless communication developing rapidly, people can almost get most of what they want at any time and anywhere. However, spectrum resources and transmission distance are limited, which severely restrict further development of wireless communication. Compared with wireless communication, fiber-optical communication has abundant bandwidth resources, huge channel capacity, extremely long transmission distance and low transmission loss and are less effected by electromagnetic interference. The only disadvantage of fiber-optical communication is not flexible enough. As a result, how to combine fiber-optical communication and wireless communication to complement each other’s advantages is the trend of future communication industry. Microwave photonics is such a fusion.Microwave photonic link, which combines advantages of both fiber-optical communication and wireless communication, are thought to be the ideal solution of future Radio Access Bearer Service. It has been a hot research area in recent years.Currently, applications of millimeter-wave technology are towards the objects of large frequency range, huge bandwidth and wide coverage. There are increasingly number of requirements for millimeter-wave systems. In phase-modulation-based coherent microwave photonic link with high dynamic range, phase controlling is one of the greatest challenges.In this paper, the basic theory, critical technologies and developing trends are introduced. Then the most important factors in a phase-modulation I/Q-demodulation system are discussed, and the method to control phase is also discussed and simulated by VPI Transmission Maker. Moreover, a scheme for improving the performance of feedback loop is proposed.