| Microwave Photonics(MWP)uses photonic devices,concepts and systems to generate,transmit and process microwave signals,to break through the limitations of conventional microwave systems on frequency,bandwidth,dynamic range,and antiinterference.MWP is used in a wide range of applications including broadband wireless access networks,radar,satellite communications,and warfare systems.Radio over Fiber(RoF)system is one of the most important applications of MWP.As broadband multiplexing technology is widely used in RoF systems,the transmission capacity increases.However,the use of broadband optical pulse carriers and the dual-sideband intensive modulation method in RoF technology makes signal transmission vulnerable to dispersion.In addition,as the signal processing bandwidth of the traditional MWP system gradually increases,the tradeoff between system bandwidth and the minimum detectable optical power limits the development of MWP systems that combine high speed with low power detection capabilities.Due to such bottlenecks of the classical MWP technology,the exploration of new technologies to improve the performance of MWP is very important.This dissertation introduces optical quantum technology into microwave photonic technology.By using the energy-time entangled two-photon source as the optical carrier,combined with low jitter and high sensitivity single photon detector and time-correlated single photon counting technology to develop the application of quantum microwave photonics(QMWP)technology.The main contribution and innovation of the thesis are mainly reflected in the following three aspects:1.Based on the energy-time entangled biphoton source,the quantum RoF system is proposed and constructed.The quantum RoF system can nonlocally recover the microwave signal on one photon from its un-modulated twin photon.Compared with traditional MWP,the recovered signal on quantum RoF improves the second-order spurious-free dynamic range and the resistance to the dispersion distortion associated with the wideband pulse carrier.Moreover,the system also provides effective enhancement of SFDR and resistance to dispersion distortion of microwave signals from a directly modulated photon carrier.These advantages demonstrate the potential and improvement for quantum RoF systems in high-capacity,ultra-fast RoF technologies.2.The QMWP signal processing method based on the energy-time entangled biphoton source is presented,and the theoretical analysis and experimental verification are carried out.Based on the correlation characteristics of energy-time entangled biphoton source,5 GHz nonlocal microwave phase shifting and 8 GHz nonlocal microwave filtering are realized.The tunability of the system to the Free Spectral Range(FSR)and the Main to Sidelobe Ratio(MSLR)is also verified.A two-dimensional parallel microwave signal processor is further realized.Compared with the classical MWP signal processing method,the QMWP signal processing method not only has good immunity to the dispersion-induced frequency fading effect associated with the broadband carrier but also promotes the development of multi-dimensional quantum information protocol,opening up new possibilities for advanced communication and networking technology.3.The relationship between nonlocal recovery and distill the RF signal out from the dispersion of high signal-to-noise ratio(SNR)microwave signals in quantum RoF systems and the temporal selection window on the coincidence distribution of the biphotons is studied.The results show that the optimal coincidence measurement temporal width is inversely proportional to the microwave signal frequency.It provides a reference for further optimization of microwave photonic signal transmission and processing systems based on the energy-time entangled source,and provides a basis for the practical development of QMWP technology. |
