Research On Microwave Photonic Harmonic Frequency Conversion Technology

Microwave photonics is the combination of microwave technique and photonics.Compared with traditional technology,it has the advantages of low loss,large bandwidth,anti-electromagnetic interference,small size and light weight.With the diversification of information service and the increasing of communication frequency,the traditional microwave mixing technology faced with the problems of limited bandwidth,inflexible frequency tunability,poor isolation as well as electromagnetic interference?EMI?,and it cannot meet the requirements of future electronic systems.Mixers based on microwave photonics can be used to solve these problems,so it has a broad application prospect,and has been widely concerned and studied in recent years.To meet the requirements of future electronic systems and solve the technical difficulties exist in photonic microwave mixers,photonic microwave mixing techniques with low frequency requirement of local oscillator?LO?,high conversion gain are studied in this thesis.The basic works of this thesis are follows:Firstly,the main devices of microwave photonic frequency conversion technology are introduced and the working principles of them are analyzed theoretically.Secondly,A simulation analysis for DSB,SSB and OCS-DSB modulation methods is executed in the VPI simulation software.Then,three key indexes of microwave photonic mixer are introduced,which are frequency conversion gain,noise figure and dynamic range.Finally,some microwave photonic frequency conversion schemes are studied,and the theoretical analysis and simulation results are given.In Chapter 4,a frequency conversion scheme based on a Sagnac loop which doubling the frequency of the LO signal is proposed,and the advantages of this scheme are as follows:reducing the frequency requirement of system by using the second harmonic of the LO signal,increasing the frequency conversion efficiency by suppressing the optical carrier,and it is especially suitable for antenna remote system because the RF and LO signals are modulated by different modulators separately.In the experiment,the 4-GHz LO signal and 25-GHz RF signal are used to get the IF signal with the frequency of 11GHz and33GHz,the IF-RF isolation can reach 32.72dB.Besides the conversion gain is-12.2dB,and the dynamic range is 102.1dB?Hz^2/3.In Chapter 5,a frequency conversion scheme based on a DP-DPMZM which quadrupling the frequency of the LO signal is presented,and the advantages of this scheme are as follows:further reducing the frequency requirement of system by using the fourth harmonic of the LO signal,increasing the frequency conversion efficiency by suppressing the optical carrier.In the simulation,the 2-GHz LO signal and the 30-GHz RF signal are used to get the IF signal with the frequency of 22GHz and 38GHz,the IF-RF isolation can reach 30d B.Besides the conversion gain is-12dB,and the dynamic range is102.5dB?Hz^2/3.