Research On Photonic Measurement Of Microwave Frequency-domain Parameters And Image Rejection Mixing

In modern electronic war,the measurement of frequency-domain parameters and image rejection mixing units are the crucial parts of the electronic reconnaissance receiver.However,with the available frequency-band expanded in war,conventional method based on electronics faces many issues,including the limited bandwidth,high loss and vulnerability to electromagnetic interfere and so on.Photonics,combing the advantages of microwave technology and optical technology,offers a new solution for the measurement of microwave parameters and microwave signal processing.For the method of frequency measurement based on frequency-to-microwave power mapping,photonic frequency measurement can instantaneously achieve the frequency value in dozens of GHz bandwidth with only hundreds of MHz even dozens of MHz error and the structure is simple and easy to be realized.Photonic Doppler frequency shift measurement not only can obtain the value and orientation of frequency shift,but also the frequency of the sent signal can be tuned in a wide range with a small measurement error.Photonic image rejection mixing has high image rejection ratio and isolation in a wide bandwidth.Besides,microwave signal processed in photonics can be effectively immune to electromagnetic interfere.However,most reported photonic frequency measurement schemes adopt more lasers or different lengths of fibers and so on,which make the adjustment of measurement range difficult.The way about how to obtain the orientation of Doppler frequency shift is complicated.Most image rejection mixing schemes use high-frequency electrical divider or phase shifter,limiting the bandwidth of system.According to these existing issues,the thesis carries on theoretical research,simulation and experimental demonstration about the measurement of frequency-domain parameters and image rejection mixing.The detailed content is arranged as following:1.Microwave frequency measurement based on Dual-polarization Mach-zender Modulator?DPol-MZM?is proposed and experimentally demonstrated.In the proposed scheme,the frequency measurement range can be easily tuned by the polarization state and the structure is simple.The experimental result verifies that the errors of system are only±200MHz in range of 2-28GHz.Theoretically,the maximum frequency measurement range in the proposed method can be up to 38.2GHz.In practical application,we can choose a suitable polarization state for meeting the demanded measurement range.2.Doppler frequency shift measurement based on DPol-MZM is proposed and experimentally demonstrated.The orientation of frequency shift can be obtained by simply judging if there is a signal in the positive or negative port of the system.The value of frequency shift can be acquired by analyzing the frequency spectrum of the port.Meantime,the frequency of the sent signal can be tuned in a wide band with the measurement error±5×10^-6 Hz in the proposed scheme.The experimental results agree well with the theories.3.Image rejection mixing based on DPol-MZM is proposed and experimentally demonstrated.The scheme has no need of wideband electrical devices,making the structure simple and bandwidth wider.Besides,the plus and minus first order sidebands are fully used to obtain a couple quadrature intermediate frequencies,which improves the available efficiency of optical signal.The experiment demonstrates that the image rejection ratio in the scheme can reach 39dB in 10-40GHz bandwidth,higher than that of the conventional electrical image rejection mixing technique.