Research On Technologies Of Receiving Of RF Signals Based On OEO

The recognition,receiving and processing of modern microwave or radio frequency(RF)signals require a high pefromance demand on the receving system,such as high resolution,wide bandwidth and anti-electromagnetic interference,so as to cope with high density and complex electromagnetic environments.Traditional electronics-based RF receiving systems encounter many electronic bottlenecks such as narrow bandwidth,high loss in high frequency,uneven frequency response and severe electromagnetic interference,which is increasingly difficult to meet the needs of receiving and processing of high-frequency and broadband signals.With the advantages of large RF bandwidth,anti-electromagnetic interference and photonic fine control and processing in the optical domain,the photonic technology overcomes the drawbacks of electronics in processing the high-frequency and ultra-wideband analog signals,and puts forward a novel solution for generation,transmission and processing of RF signals through photonics method.The optoelectronic oscillator(OEO)employs an opto-electronic feedback structure with low loss and large time delay to achieve a closed feedback loop with a high quality factor in order to generate an oscillating signal with high spectral purity and low-phase-noise,and the OEO therefore has a great potential for acting as a local oscillator(LO).With the help of photonically generated LO signal through the OEO,the research on the key thechnoloy of recognition and receiving of RF signals conmbining with OEO has a scientific significance and theoretical value.In this dissertation,theoretical model and phase noise characteristics of OEO are firstly summarized,and two basic OEO-based photonic RF receiving structures are introduced.Then,the characteristics of the coupled opto-electronic oscillator(COEO)are explored.A channelized RF amplification scheme based on mode-locked fiber laser is proposed.Next,the supermode noise of COEO is optimized through an opto-electronic hybrid filter and a photonic RF receiving scheme based on COEO is proposed.Finally,several OEO-based photon heterodyne receivers and image-frequency rejection receivers are proposed,their operational principles are analyzed and experimental verification are carried out.The main research contents of this dissertation are as follows:1.A photonics-based method for channelized amplification of weak signals is proposed based on the mechanism of the active harmonic mode-locking of the fiber laser.The RF gain,Q value in a single-channel and dynamic range of the system are discussed and experimentally verified.2.To optimize the phase noise performance of COEO,a super-mode noise suppression scheme for COEO based on an opto-electronic hybrid filter is proposed,which reduces the spurs of the oscillating signal and improves the phase noise performance from the far-end.Its operation principle is theoretically analyzed and verified by experiments.A photonic RF receiving scheme using optical frequency combs of COEO with phase correlation and low phase noise is studied,and the photonic RF down-conversion is achieved through the photonics generated frequency tripling LO.The system performance for receiving broadband signals is verified by experiments.3.In the research of OEO-based photonic heterodyne receivers,a photonic RF scanning receiver based on single sideband tunable OEO is proposed,which overcomes the dispersion induced power fading effect in a long-distance transmission with double-sideband modulated signals.To enhance the compactness of the system,a photonic RF scanning receiver based on a dual-electrode modulator is constructed.The scheme employes OEO generated LO with low phase noise,and partially suppresses the optical carrier to mitigate the mixing spurs as possible.The related experiments are verified.Finally,a photonic RF receiver based on a frequency doubling OEO is designed.The scheme realizes the function of frequency down-conversion based on a frequency doubling OEO utilizing low frequency components,and experimental verification is carried out.4.In the research of OEO-based photonic image rejection receiver,an image rejection RF receiver based on bias point control is proposed.Through properly setting the bias point of the modulator,the image distortion is effectively rejected and advantages of low phase noise LO by OEO and compact size of the scheme still are kept.The operating principle is theoretically analyzed and experimentally verified.To extend the operating bandwidth of the system,an image-frequency rejection receiver based on a frequency doubling OEO utilizing two lasers with different wavelengths is studied.Through employinng two different wavelengths in the OEO loop and the photonic conversion path,the optimal oscillation state of the OEO is guaranteed and the optical carrier in the photonic mixing path is effectively suppressed to reduce the mixing spurs.The scheme implements a photonic RF down-conversion by a frequency doubling OEO,and the theoretical derivation and simulation verification of the scheme are performed.