Research On Microwave Photonic Channelization And Frequency Conversion Technology

In modern complex electromagnetic environment,signals that need to be processed at the same time are more and more complex,and the bandwidth of singals that needs to be processed is also keep growing.The narrowing of broadband signals is particularly important.Microwave photonic channelized receiving technology is considered as one of the most effective methods to process broadband signals in microwave and millimeter wave receivers.Microwave mixing can realize the up-down conversion of microwave signals,and has been widely used in radar,electronic warfare,military,wireless communications,satellite communications and other fields.Due to the limitation of bandwidth,poor frequency tunability,low isolation and sensitivity to electromagnetic interference,traditional electric mixing technology can not meet the requirements of receivers with high precision.Microwave photonic mixing technology overcomes the bottleneck of electric mixing technology,and it has been studied more and more widely.Faced with the future development of electronics,aiming at the bottleneck of mixing technology and channelized receiving technology,this paper studies the channelization and frequency conversion technology based on microwave photonic with high frequency range and large instantaneous bandwidth.The specific research contents are as follows:1.Firstly,two most commonly used optical modulation techniques,direct modulation and external modulation,are introduced.Then physical model analysis and mathematical formula derivation of several electro-optic modulators involved in external modulation are carried out,including phase modulator,Mach-Zehnder modulator,dual-parallel Mach-Zehnder Modulator and dual polarization quadrature phase shift keying modulator.The working principle of several commonly used modulation modes id analyzed with illustration.Then two kinds of photoelectric demodulators are introduced,including photodiode and balanced photodiode.Finally,three technical indicators related to microwave photonic channelized receiving technology and frequency conversion technology are introduced,namely instantaneous bandwidth,noise figure and spurious-free dynamic range.2.Several existing optical frequency comb generation schemes are analyzed.Then combining microwave photonic mixing technology with channelized receiving technology,a dual-effect channelized receiving scheme based on dual optical frequency comb is proposed.This scheme can simultaneously use two sideband signals of each comb line for channelized receiving,and generation of local oscillator optical comb is not affected by DC drift.The theoretical derivation and simulation of the scheme are carried out.In the simulation,four signal comb lines generate eight broadband signal sidebands.The 7 GHz broadband signal is successfully divided into seven sub-channels,the bandwidth of each channel is 1 GHz,and the error vector amplitude of each channel is less than 4%.Then a channelized receiving scheme with image rejection based on dual optical comb is proposed.The scheme can also achieve the same IF reception of broadband signals.In simulation,5GHz broadband signals are down-converted to five 1 GHz sub-channels,and the error vector amplitude of each channel is less than 1.5%.3.A microwave photonic image rejection mixing scheme based on DP-QPSK is proposed and simulated.This scheme does not need high frequency phase shifter.The system has simple structure and wide operating frequency range.In simulation,the image rejection ratio reaches 44.8dB which is higher than the maximum image rejection ratio achieved by traditional electronic image rejection mixer.The spurious-free dynamic range is 110.6 dB?Hz^2/3.