Research On Gain And Dynamic Range Optimization Methods Of Microwave Photonic Downconversion

As the demand for communications increases,the communication bandwidth and signal frequency continue to increase.However,the processing bandwidth of signal processing system is limited,and for high-frequency and large-bandwidth signal received,it is necessary to downconvert the frequency of the received signal to a low or intermediate frequency before processing.It is limited and scant to process high-frequency signals by traditional electrical downconversion technology,while microwave photonic downconversion technology has significant advantages such as large bandwidth,wide frequency band tunability,high isolation,and no electromagnetic interference,which has a large application and receives extensive attention and research.However,the gain and dynamic range of common microwave photonic downconversion methods is limited,thus,facing the development needs of the future communication system,and aimming to the shortages of the existing microwave photonic downconversion technologies,it is significant to study the gain and dynamic range optimization methods of microwave photonic downconversion.In this paper,the research progress and basic theories of microwave photonic downconversion technology is summarized,then performance parameters of the link is analyzed,and the microwave photonic downconversion methods based on cascaded Mach-Zehnder Modulator(MZM)is deeply studies,meanwhile,theoretical and simulation analysis is performed on this basic downconversion method.Based on it,a microwave photonic downconversion method based on Polarization Division Multiplexing Mach-Zehnder Modulator(PDMMZM)and a microwave photonic downconversion method based on Polarization Division Multiplexing Dual-Parallel Mach–Zehnder Modulator(PDM-DPMZM)are proposed aiming at the goal of improving the gain and dynamic range of microwave photonics downconversion.In the microwave photonic downconversion method based on PDM-MZM,the DC bias voltage and the setting conditions of the local oscillator signal are obtained through theoretical analysis and mathematical derivation.Combined with the balance detection method,the gain can be improved and the dynamic range of the link can be optimized.In the microwave photonic downconversion method based on PDM-DPMZM,from the perspective of suppressing third-order intermodulation distortion,theoretical analysis and mathematical derivation are conducted to get the specific parameters affecting the third-order intermodulation distortion,then the linearization condition for suppressing third-order intermodulation distortion is obtained.According to the linearization condition,by adjusting the system parameters to meet the linearization conditions,the third-order intermodulation distortion is suppressed,and the dynamic range is improved.Combined with the balance detection method,the conversion gain is optimized as well.Besides,the highly-integrated electrooptic modulation devices are used in the gain and dynamic range optimization methods proposed in this paper,which can greatly simplify the link structure and improve the system stability.In summary,the gain and dynamic range optimization methods of microwave photonic downconversion proposed in this paper optimize downconversion gain and dynamic range,and fully utilize the advantages of microwave photonics technology in downconversion applications.It has a certain theoretical significance and practical value for the application of microwave photonics in electronic systems.