Research On Analog-to-digital Conversion Technology Based On Optical Nonlinear Transmission Lines

Analog-to-digital converter(ADC)is an important device that converts an analog signal that changes continuously with time into a digital signal that is discrete in time.ADCs have very important applications in civil and military fields such as modern wireless communication systems and radar detection systems.Electronic analog-to-digital converters cannot meet the increasing application requirements of digital systems due to the physical limits of semiconductor carrier mobility,sampling time jitter,and the effects of electronic comparator uncertainty.The photonic assisted ADC fully combines the advantages of high sampling rate,low time jitter,and high quantization accuracy of electronic ADCs to achieve real-time analog-to-digital conversion and high effective number of bits.In this thesis,the analog-to-digital conversion technology based on optical non-linear transmission lines is taken as the research object.The related fundamental concepts and principles are studied.A scheme of analog-to-digital conversion system based on optical nonlinear transmission line is proposed.This thesis focuses on the work including the overall system design,the theoretical analysis and numerical simulation of the system program,the construction of the system platform for experiments,and the system performance analysis.The main research contents of this thesis are as follows:(1)The research progress,fundamental concepts and principles of optical ADCs are introduced.Among them,the research significance of photonic sampling analog-to-digital conversion is emphasized.This thesis focuses on the principles and performance parameters of photonic sampling analog-to-digital conversion technology as well as theory of cavity-less optical pulse source and the key technology of analog-to-digital conversion based on optical nonlinear transmission line.(2)An analog-to-digital conversion system scheme based on optical nonlinear transmission lines is proposed.This scheme uses the process of chirp generation and chirp compensation in the optical nonlinear transmission line to achieve the generation of high repetition rate and low time jitter optical pulse sequences.High-speed photonic sampling of broadband microwave signals can be achieved by combining broadband electro-optic modulation technology and optical time decomposition multiplexing technology.Finally,high-speed and high-precision optical analog-to-digital conversion can be achieved by utilizing multi-channel data reorganization technology,digital domain equalization and linearization processing technology.(3)Numerical simulation of the analog-to-digital conversion system scheme based on the optical nonlinear transmission line was carried out.The feasibility of the scheme was proved theoretically.The relevant parameters were optimized.Based on the theoretical derivation and numerical simulation,the scheme was experimentally verified.An analog-to-digital conversion with a sampling rate of 8GS / s and an effective number of 4 bits was realized.