Optical Design Of Wave-Front Matching Frequency-Doubling System For Ultrashort Pulses

Ultra-short pulses with high intensity and wide spectrum were used as ultra-strong,ultra-fast light and ultra-accurate light clocks.Their application has been deepening in various research fields,and they have become effective scientific tools to help people explore the physical and chemical processes under strong electromagnetic fields,discover and explore the changes in the microscopic world,and reach precise measurement.The appearance of femtosecond pulses promotes the research of frequency doubling.Wave-front matching method is an effective way to realize frequency doubling,which can improve the conversion efficiency on the premise of guaranteeing the pulse quality.By combining wave optics with geometric optics,a frequency doubling system based on grating and prism is designed by using ray tracking module in optical design software.The design process not only eliminates the complicated theoretical calculation,but also is more intuitive.In this paper,the ray tracing method in optical design software and the basic principle of nonlinear optics are used to design four kinds of phase matching frequency doubling systems for ultra-short pulse wavefront.The main research contents are as follows:First on the nonlinear optical theory,phase matching is introduced and the group velocity matching conditions,the matching of wavefront model is set up,the wavefront tilt coupled wave equation was deduced and the small signal approximation,the analytical solution of the equation of wavefront matching frequency doubling allowed Angle and Angle as an important standard of evaluating wavefront matching system.Secondly,a wavefront matching system based on double grating,four grating,double prism and four prism was established in ZEMAX.According to the constraint conditions of the system,the group velocity dispersion of the system was controlled by a custom macro program,and the evaluation function was established by combining the permissible Angle of frequency doubling.Again,in order to meet the requirements of double frequency grating angular dispersion times system,select the appropriate parameters as variables in ZEMAX double grating,four grating,double prism,four prism wavefront matching system,using the established evaluation function,optimize the system,the structure parameters,ensure all frequency component in the pulse system into the nonlinear crystal can realize phase matching,eliminate the time and frequency doubling output pulse chirp chirp and space to complete combined beams;Finally,the frequency doubling system of four kinds of structure of tolerance analysis,selection of evaluation function as an evaluation standard system,to obtain the tolerance of the most sensitive surface of the system in the building process of these parameters for precise control,system quality,and system management,to the difficulty of the system size,the quality of the system,system adjustment and difficult aspects analysis,the results will help us with reference to specific system design goals,selecting the optimum configuration scheme.Firstly,the theoretical model of wave-front matching was established based on nonlinear optics theory,and the allowable Angles of wave-front matching frequency doubling was obtained,which was used as an important standard to evaluate the wave-front matching systems.