Research On Microwave Photonic Frequency Conversion Technology Using Dual-Parallel Mach-Zehnder Modulator

Traditional microwave mixing technology,restricted by "electronic bottlenecks" such as bandwidth and electromagnetic interference,cannot meet the development needs of high frequency broadband and multi-function integration of integrated electronic system.Microwave photonic frequency conversion technology has become an important technical means of RF front-end system due to its advantages of large bandwidth,low loss,high isolation and strong anti-electromagnetic interference ability,which has attracted the attention of researchers all over the world.However,microwave photonic frequency conversion scheme generally has some technical problems,such as single function,poor gain stability,low signal-to-noise ratio and so on,which cannot conform to the development trend of integrated transceiver function and high frequency conversion efficiency of communication system.With consideration of the above problems,this paper uses the modulation characteristics of dual parallel Mach Zehnder modulator to study the conversion function,gain flatness,signal-to-noise ratio and other aspects of microwave photonic frequency conversion system.Main results of the work are as follows:1.In this thesis,a broadband microwave photonic frequency conversion system based on parallel double parallel Mach Zehnder modulator is designed.By combining the dual parallel Mach Zehnder modulator with tunable optical filter,and setting the bias voltage of the modulator reasonably,the microwave signal in the frequency range of 2?30GHz can be modulated by suppressed carrier single sideband with high sideband rejection ratio,and the up and down conversion functions can be realized,which solves the problem of single function of the traditional microwave photonic conversion system.And the spurious signal rejection ratio can reach more than 50dB in the whole bandwidth.2.In this thesis,a broadband universal microwave photonic frequency conversion system prototype is designed and implemented,which can convert the signals of different frequency bands and realize the integration of transceiver function.As the receiver,the system can down convert the 8-40GHz signal to 2-6GHz,and the image rejection ratio is greater than 27dB.As the transmitter,the system can up convert the 2-6GHz signal to 10-40GHz,and has more than 43dB isolation between RF and LO.The rejection ratio of undesired signal is more than 50dB,which is more than 20dB higher than other microwave photonic frequency conversion schemes.In the whole working frequency band,the gain flatness of the system is less than 10dB,which is more than 10dB higher than the traditional frequency conversion scheme.