The Researches Of High Dynamic Range Microwave Photonic Link And All-optical Frequency Down-conversion Technology

Microwave photonic technology has many advantages, such as low loss, light weight, low power consumption, wide instantaneous bandwidth, immunity to electromagnetic interference, high dynamic range, etc., and has a wide range of applications in radar system, satellite communications, measurement and detection systems and other areas. In this paper, we built a simulation model of the microwave photonic link, studied the dual-wavelength microwave photonic link linearization technology and achieved the all-optical broadband microwave signal down-conversion based on cascaded phase-modulators. The works in this dissertation include:1. Modeling and Simulation of microwave photonic linkIn order to identify the relationship among the key parameters such as link gain, noise figure, nonlinear distortion and dynamic range, the modeling and simulation of the microwave photonic link is established. The simulation results show that the increase of optical detection current can improve the gain and dynamic range of the link, but it makes the link noise figure increases. At the same time, reducing the modulator half-wave voltage, we can improve the link gain and reduce the noise factor, but it will reduce the dynamic range. Therefore, to improve the performance of the microwave photonic link, we need to consider the impact of various parameters.2. Dual-wavelength microwave photonic link linearization technologyA dual-wavelength linearized microwave photonic link based on an Mach-Zehnder Modulator (MZM) modulator is investigated to achieve 25dB third-order intermodulation distortion suppression. At the same time, the scheme is suitable for long-distance transmission of microwave signals. Experiment results show that, the Error Vector Magnitude (EVM) of a Quadrature Phase Shift Keying (QPSK) signal at IMb/s rate after 5.1km standard single-mode fiber transmission is 18.26% and 8.06% before and after the linearization respectively.3. All-optical broadband microwave signal down-conversion technology based on cascaded phase-modulators All-optical broadband microwave signal down-conversion technology based on cascaded phase-modulators has been studied. The all-optical down-conversion of 2-18 GHz broadband microwave signals with>90dB·Hz2/3 dynamic range has been experimentally demonstrated by using interferometer demodulation technology based on cascaded phase modulators. And 15dB of third-order intermodulation distortion suppression has been achieved using coherent demodulation technology based on cascaded phase modulators.