Microwave Photonic Frequency Converter Based On A Mode-locked Laser

Microwave photonics is a new discipline that combines the advantages of optics and microwave science.Microwave photonic technology can integrate the advantages of low optical loss,large bandwidth,and reconfigurable into the microwave signal processing system,so as to achieve the generation,transmission,conversion and processing of microwave signals.In modern life,microwave signal frequency conversion technology is widely used in various fields such as communication and radar.Due to the advantages of microwave photon frequency conversion technology,such as large bandwidth,simple structure and resistance to electromagnetic interference,it has become a research hotspot.This thesis proposes two technologies for microwave photonic up converters based on mode-locked lasers and microwave photonic converters based on swept fiber lasers in response to the needs of new microwave photonic converters in communication systems:This thesis proposes a new microwave photon upconverter technology based on mode-locked lasers.This technology has good tunability and can achieve high frequency output with a small local oscillator frequency.At the same time,the signal quality of the output frequency conversion signal of the microwave photon upconverter based on the mode-locked laser is also analyzed,and the data processing is performed by the computer.The restoration of the original signal is completed.Finally,50 Mbps with a center frequency of 1GHz is realized through experiments.The QPSK signal is upconverted to 6.00002 GHz and6.00004 GHz,and the signal quality remains good during the upconversion process.When the received optical power is-3.0 d Bm,the back-to-back transmission bit error rate(BER)is 10-9.In this thesis,a microwave photonic frequency converter technology based on a swept fiber laser is proposed.Compared with the traditional electrical frequency conversion technology,this technology has the characteristics of large bandwidth and up and down conversion.In this microwave frequency converter system,a broadband swept fiber laser is used to generate a frequency-chirped optical carrier and send it to a Mach-Zehnder modulator.Then send the modulated signal to the dispersion device,and use the dispersion of thedispersion device to compress or expand the optical pulse waveform.After photoelectric detection,microwave signals with frequency up or down conversion can be generated.In addition,the MATLAB software was used to simulate the design of the microwave photonic inverter and verify the theoretical model established to analyze the performance of the inverter system.In the experiment,the up-conversion and down-conversion of the system were achieved by switching the sign of the chirp rate of the swept fiber laser,and finally the conversion of the input microwave signal from 5 GHz to 5.577 GHz and 4.936 GHz was completed.