Research On Broadband Laser Spatial Chirp Matching Frequency Doubling Technology

In an inertial confinement fusion laser device,the performance of the harmonic conversion system has a significant impact on the target laser.In order to improve the unifomity of target surface,SBS and SRS,harmonic conversion of high-efficiency broadband light is of great significance.In order to achieve high-efficiency wideband frequency multiplication,this paper proposes a new type of spatial chirped pulse,and analyzes its feasibility in high-efficiency broadband frequency doubling process.Taking numerical simulation as the main means,the contradiction between conversion efficiency and bandwidth is discussed in detail,and the feasibility of the multiplier scheme with spatial chirp pulse is analyzed,and finally obtained good output results.The main work of the thesis includes:1.This paper establishes the basic system structure and theoretical basis of the frequency doubling scheme which is based on spatial chirped pulse,and then establishes the theoretical model of the scheme.By broadening the fundamental pulse into a spatial chirped pulse,we can obtain narrow-band light at a local-spatial-position,thereby achieving higher conversion efficiency on the basis of broadband fundamental light.2.The frequency doubling scheme based on Fourier transform is proposed.We give the basic structure of the system,and build a mathematical physics model based on it.At the same time,in order to solve the phase mismatch of the edge frequency components,we propose a way of splicing crystals to further expand the phase matching range.In further research,we specifically analyzed the effect of crystal stitching error on the output.In this scheme,we find that the frequency doubling process occurs on the frequency plane,which can greatly reduce the influence of splicing error.3.In combination with engineering applications,we propose a spatial dimming scheme that can be stably transmitted in space.In this scheme,by adjusting the parameters of the stretcher,we can effectively adjust the parameters of the spatial dimming after the widening.At the same time,through adaptive optics and wave-front control,the scheme can further expand the matching range and avoid phase mismatch of edge frequencies.