Optimization Of Electro-Optical Sampling And Demultiplexing In Photonic Analog-to-Digital Converter

In recent years,photonic analog-to-digital conversion(PADC)technology is utilized to overcome the performance bottlenecks in traditional electronic analog-to-digital conversion(ADC)technology.The PADC system consists of a photonic front-end and an electronic back-end and it combines the high performance of photonic technology with the convenience of electronic technology.In this sense,PADC system provides an ideal solution to signal processing for the next generation radar and communication.In many previous studies,the researchers paid much attention to the performance of PADC,such as Effective Number of Bits,system sampling rate and sampling bandwidth.At the basic principle level,great progress has been made in microwave photonic link analysis,link model design,and channel composite schemes.Nowadays,it is essential that the performance of the PADC system should meet practical requirement.In terms of engineering,the most important technical difficulties faced by the PADC system are the simplification of operation,universality,and stability.Based on the previous work of the high-speed and high-precision PADC system,this study aims to improve the system in the aspects of system automation and stability optimization.The main contents of the thesis are summarized as below:(1)The working mechanism and mathematical model of the MZM are given.The nonlinear phenomena and the optimum bias point drift phenomenon are verified in theory and experiment.The influence of these two phenomena on the PADC system is emphasized.(2)Aiming at the shortcomings of insufficient stability on the channel-interleaved PADC system,a feedback optimization model based on system link characteristics is demonstrated.The rationality of the feedback system is verified.In this way,the system operation stability is improved to a large extent.Experiments show that the amplitude mismatch caused by offset drift drops from 3.4 d B to 0.3 d B.(3)Considering the defects found in the preliminary test of the high-speed and high-precision PADC system prototype,the structure of the system prototype is improved with a feedback optimization model and automatic controlling software according to our accumulated testing experience.Optimized system not only improves the automation level of the system prototype,but also greatly improves the ability of the system prototype to work stably for a long time.