Research On Optical Frequency Comb Generation Based On Frequency Shift Feedback Structure And Its Application

With the rise of mobile Internet and the rapid development of modern communication technology,people's demand for information content presents explosive growth,which also promotes the continuous improvement and maturation of microwave technology and optical fiber communication technology.The combination of optical fiber communication and microwave technology has given rise to a new field of research: microwave photonics.Combining the advantages and characteristics of microwave technology and optical fiber optics,microwave photonics has great potential in the fields of arbitrary waveform generation,photon signal processing and instantaneous frequency measurement.Laser light source with comb frequency spectrum with large amount of equispaced wavelength is called optical frequency comb.As the hinge connecting microwave and optical wave,optical frequency comb is an essential and key part in the research direction of microwave photonics.The application prospect based on optical frequency comb is also very broad.Therefore,the generation of high quality optical comb is of great significance for the research and development of microwave photonics.In this paper we mainly study the generation of optical frequency combs and the application of optical frequency combs.1.Theoretical analysis and experimental results are given for the method of generating optical frequency comb based on the cascade of electro-optic modulator.Combined with the simulation results,the conditions for the generation of high-quality optical comb were analyzed,and the experimental verification of the optical comb generated by the electro-optic modulator based on the dual drive Mach–Zehnder Modulator was completed.The optical comb with 11 stable combs with a bandwidth of 100 GHz and a flatness of up to 2 dB could be generated.2.Theoretical analysis and experimental results are given for the method of generating optical frequency comb based on frequency shift feedback structure.Combined with the simulation results,the condition of generating high-quality optical comb was analyzed,and the experimental verification results of generating optical comb based on frequency shift feedback structure were completed.The optical comb with 30 comb teeth and a bandwidth of 375 GHz and a flatness within 5 dB could be generated.3.An innovative instantaneous frequency measurement scheme based on cyclic frequency shifting is proposed,and a step-type optical frequency comb is generated by using cyclic frequency shifting structure,and theoretical derivation and simulation verification are given.The stepping optical comb can be used to measure the frequency of microwave signal in a wide frequency range and it can save the measuring bandwidth of photodetector.In the experiment,the frequency of microwave signals in the range of 0-40 GHz was measured,the error was within 0.40 MHz,and only the detector bandwidth of 4 GHz was needed.