Research On The Key Technologies Of Photonic Generation Of Microwave Signals

The photonic generation of microwave signals is the most important research content of microwave photonics and it has broad application prospects.It has the advantages of high frequency,low phase noise and compact structure,and can solve the electronic bottleneck problem faced by the microwave signal generated by the electronic field.Therefore,photonic generation of microwave technology is more and more valued by research institutions,and is increasingly used in the field of radio over fiber systems,radar systems,satellite communications,etc.This paper mainly studies the photonic generation technology of multi-frequency and multi-waveform microwave signals,and mainly uses external modulation method to generate frequency multiplication signals and the multi-waveform signals.The paper proposes two kinds of photo-generated frequency multiplication structures and a photogenerated multi-waveform structure.The main work of this paper includes:1.A multi-frequency scheme based on dual-polarization Mach-Zehnder modulator(DPol-MZM)is proposed,the microwave frequency quadrupling,octupling,and 12-tupling signals are generated by the same system structure.The modulation index of the modulator in the frequency quadrupling scheme is adjustable,when it varies between 0.39 and 3.53,the radio frequency spurious suppression ratio(RFSSR)of the output signal is higher than 20 dB,the highest is 47 dB;when the modulation index of the modulator is 2.4048,the output is a frequency octupling microwave signal that RFSSR is 24dB;when the modulation index of the modulator is 5.1356,the system can output a frequency 12-tupling microwave signal with the RFSSR of 30 dB.Firstly,the theoretical derivation of each scheme was carried out,and then the theories were verified by the OptiSystem simulation software.Combined with Matlab software,the influence of non-ideal factors on system performance was analyzed,such as the extinction ratio of the modulator,DC bias voltage,RF driving voltage,the phase shift of the phase shifter and the angle of the polarizer.2.A multi-frequency scheme based on polarization division multiplexing dualparallel Mach-Zehnder modulator(PDM-DPMZM)is proposed.The same system structure is used to generate microwave frequency 12-tupling and 24-tupling signals.When all modulators are biased at the maximum transmission point and the modulation index is 5.1356,a frequency 12-tupling signal with the RFSSR of 29 dB can be obtained;when the sub-modulators of dual-parallel Mach-Zehnder modulators(DPMZM)in PDMDPMZM are biased at the maximum transmission point,the main modulators of two DPMZMs are biased at the minimum transmission point and the modulation index is 7.5883,a 24-tupling signal with the RFSSR of 29.5 dB can be obtained.Firstly,the theoretical derivation of each scheme was carried out,and then the theories were verified by the OptiSystem simulation software.3.Testing the odd-order sideband suppression modulation and even-order sideband suppression modulation spectrums of the intensity modulator.Then,the experimental systems of double frequency based on a intensity modulator and frequency quadrupling based on two cascaded intensity modulators are built,and the double frequency signal with RFSSR of 21.5dB and the frequency quadrupling signal with RFSSR of 36 dB are generated.4.The structure of the photonic generation of multi-waveform microwave signals using dual-polarization Mach-Zehnder modulator is proposed.By appropriately selecting the system parameters such as modulation index,DC bias voltage and the phase of the phase shifters,the double frequency triangular waveform and square waveform both with the repetition rate of 20 GHz,that is,the period of 50 ps,and a sawtooth waveform with a repetition rate of 10 GHz,that is,the period of 100 ps,are generated from the 10 GHz sinusoidal RF driving signals,respectively.Firstly,the principles of the schemes are analyzed,then the theories are verified by OptiSystem simulation software.