Research On The Performance Of The Guiding Broadband Reception For RF Signals Based On Microwave Photonics

With the advent of the information age,the increasing demand for the high-speed communication has promoted the development of communication signals in the direction of high frequency band and large bandwidth.Traditional electronic receivers can no longer meet the requirements of receiving multi-band and large-bandwidth signals in a complex electromagnetic environment.In recent years,microwave photonics uses optical methods to break through the limitations of electronics,and has the advantages of large bandwidth,low loss,small size,light weight,and anti-electromagnetic interference.As optoelectronic devices become more and more mature,microwave photonics has gradually been applied in wireless communication and microwave radar systems,and reveals unique advantage in multi-frequency band and large bandwidth.This dissertation will focus on the microwave photonics-based frequency guiding broadband microwave receiver and its key technologies including instantaneous frequency measurement and RF signal generation.The main research content is as following:In terms of the instantaneous frequency measurement,we first investigate the frequency mapping relationship between the measured RF signal and its down-converted intermediate frequency signal in the case that the local light signal is a tunable singlefrequency optical signal or an optical frequency comb,respectively.According to the inadequacies,including prerequisite and frequency ambiguity,in these two cases,we propose an instantaneous frequency measurement scheme based on an amplitude varying optical frequency comb.In this scheme,the frequency of the RF signal can be obtained through the frequency and power information of the down-converted intermediate frequency signals.Then,we simulate the instantaneous frequency measurement for single-tone and multi-tone RF signals and analyze the measurement error.Meanwhile,the influence of the laser RIN noise on the power ratio of the intermediate frequency signal is also investigated.Finally,we design and setup a proof-of-principle experimental system.In the experiment,the frequency measurement range of 2-12 GHz and the measurement error of 1.5 MHz are achieved using a signal analyzer operating in the frequency range of DC-2 GHz,which can realize frequency monitoring of RF signals in the complex electromagnetic environment.In terms of the RF signal generation,we first introduce the basic structure and opterating principle of the single-loop and dual-loop optoelectronic oscillators,and investigate their oscillation modes and single sideband phase noise.Aiming at the issue of the need of optical filters or RF filters to select one mode among many oscillation modes,we propose the optoelectronic oscillator based on the Vernier feedback loop,which can implement single-mode oscillation without optical or RF filters.And the frequency of the generated RF signal can be tuned by adjusting the delay time difference between different paths and not limited by filters.The influence of the length of the fiber loop,the number of the paths and the delay time difference on the frequency,phase noise and spurious suppression ratio of the generated RF signal is investigated.Finally,we design and setup a proof-ofprinciple experimental system and achieve the frequency tunable range of 3.07-4.72 GHz.When the fiber length is 100 m,the generated RF signal has the single sideband phase noise of-99.60 d Bc/Hz at the offset frequency of 10 k Hz.In terms of the broadband microwave reception,we first propose the basic structure and operating process of the frequency guiding down-conversion reception system based on microwave photonics.And we investigate the suppression of out-of-band signals by the limited frequency response of the photodetector in the microwave down-conversion based on carrier-suppressed double sideband modulation.Then,we simulate the downconversion reception for the linearly chirped pulse signal and binary phase encoded pulse signal and the selective reception of multiple signals.Finally,we design and setup a proofof-principle experimental system for the down-conversion reception.In the experiment,three types of the signals with the frequency around 25 GHz,including the single-tone continuous signal,linearly chirped pulse signal and binary phase encoded pulse signal are down-converted to the intermediate frequency signal with the frequency of less than100 MHz.