Numerical Simulation On The Broadband And High-efficiency Third-harmonic Generation Of Super-luminescent Light

Energy is the driving force for the development of human society and one of the key factors for achieving sustainable development.Several countries are actively studying controllable nuclear fusion power generation,and laser-driven inertial confinement fusion is regarded as the most likely technical solution to achieve controllable nuclear fusion.In this thesis,based on the requirement of inertial confinement fusion for a broadband and efficient third harmonic generation,the theoretical analysis and numerical simulation is conducted to expand the third harmonic generation of super-luminescent light and compensate for the super-luminescent light third harmonic generation by other methods.The research on the amount of mismatch provides good reference for the experimental research on super-luminescent light.The main content is divided into four parts.1.The physical model of third harmonic generation process and the main influence factors in the process of realizing broadband and efficient frequency tripling are analyzed.The mechanisms of various schemes for improving the efficiency and bandwidth for frequency tripling process are theoretically derived,and the advantages and disadvantages of each scheme in application are analyzed2.The numerical solutions of harmonic generation process with high power laser are derived.The numerical model of super-luminescent light is established according to the literatures.Combined with the numerical model of super-luminescent light,the numerical simulation of direct third harmonic generation of super-luminescent light is realized.By analyzing the phase mismatch distribution in the process of third harmonic generation,the characteristics of frequency spectrum and conversion efficiency caused by the characteristics of super-luminescent light are discussed.3.The evolution of the efficiency and spectral characteristics of the sum frequency of mixing second harmonic wave of super-luminescent light with the high temporal coherence fundamental wave is analyzed.In addition,several schemes are compared and analyzed,including the direct frequency tripling process of super-luminescent light,the sum frequency of mixing narrowband light with super-luminescent light of different bandwidth.After compared with the direct frequency tripling,it is found that the scheme of mixing broadband super-luminescent light with narrowband light can effectively reduce the influence of group velocity mismatch on the third harmonic generation progress.The frequency tripling efficiency of the super-luminescent light can be increased to 44%,and the output frequency tripling bandwidth can reach 1.9 THz.The results can be used as a reference for the design and experimental study for the third harmonic generation system.4.The influence of grating dispersion on the second and third harmonic generation processes is analyzed based on the spectral dispersion method of third harmonic generation process of type I/II phase matching.The simulation process of the third harmonic generation of chirped light and super-luminescent light is carried out,and their efficiency curve and spectrum shape are analyzed.By comparing the phase mismatch before and after the spectral dispersion compensation,the reason why the spectral dispersion method has little improvement on third harmonic generation of the super-luminescent light is discussed,and the possible ways to improve the compensation are proposed.