Research On Microwave Photonic Waveform Signal Generation And Optical Switching

Microwave photonic waveform signal generation and optical switching technology are two indispensable technologies in the integration of multi-function radio frequency detection.In recent years,due to its inherent disadvantages,such as serious electromagnetic interference,large transmission loss,limited bandwidth,high cost and large volume,the development of traditional electronic technology has been limited,and the research progress has hit a wall everywhere.However,radar,satellite communications,electronic reconnaissance has more and more requirements for bandwidth,frequency band,tunability,loss,etc.And they tend to develop in the direction of multi-functional integration.As a new subject,microwave photonics not only inherits the advantages of optical fiber communication but also overcomes the troubles brought by microwave communication.It has many advantages,such as large bandwidth,high frequency band,small attenuation,strong tunability,small size and free from electromagnetic interference.It has obvious advantages in generating waveform signals by using microwave photonics.Optical switching technology has been widely used due to its advantages of high speed,large bandwidth,high density and low cost.In this paper,microwave photonic waveform signal generation and optical exchange technology are studied.The research background and basic theory are summarized,and the proposed scheme is analyzed in principle and verified by simulation.The main work is as follows:1.A scheme of cascaded Mach-Zehnder modulator(MZM)to generate microwave waveform signal is proposed and verified by simulation.In this scheme,two modulators have polarization correlation to the modulation efficiency,so that the output light of the cascade two MZM is polarization multiplexed light,which can beat the frequency independently in the photodetector to generate square wave and triangle wave signals of double frequency,and shorten the pulse period of the generated signal,and more,the scheme can also generate single frequency sawtooth signal.The scheme is simple in structure,without the use of electric filters and complex devices,the feasibility of the scheme is strong.2.A scheme of generating frequency doubling triangular and square waveform based on double polarization Mach Zehnder modulator(Dpol-MZM)is proposed.It is analyzed in principle and studied by simulation.The principle and modulation mode of the scheme are simple,and the obtained electric signal harmonic component is pure.After the photodetector beats the frequency,the fourth harmonic is offset,the second harmonic and the sixth harmonic are strengthened,the repetition rate of the generated signal is effectively increased,and the double frequency waveform signal is obtained.3.A scheme of generating microwave waveform by using double polarization normal phase shift keying modulator(DP-QPSK)is proposed,and discusses the scheme from two aspects of principle analysis and simulation.The simulation results show that the scheme can generate triangular wave and square wave signals at the same time.The scheme is simple and easy to implement,and does not use any electric phase shifter,electric filter,etc.,which enhances the flexibility of the system,and does not need to strictly control the amplitude of the RF signal.4.An optical switching structure using multicast switch(MCS)and unicast switch cascades is proposed.This structure is a generalized nonblocking three-level switching structure with multipath property.This structure enhances the scalability of the multicast optical switching system,and effectively reduces the signal attenuation while realizing the multicast function.Finally,a simulation study is carried out to verify the feasibility of the scheme.