Optimized Design And Experimental Research On High Efficiency Frequency Tripling System In The Hundred-joule Solid Laser

As a critical part of the hundred-joule solid laser, a frequency tripling systemwith high beam quality, high operation stability and high efficiency has importantsignificance on reducing operation risk and requirement for input intensity as wellas improving absorption efficiency. In this dissertation, contraposing the Nd-dopedphosphate glass laser system with100J energy output, schemes of frequencytripling are systematically studied and simulated. In addition, the offline and onlineexperiments are carried out.This thesis is divided into three parts. The first one is the study and simulationof schemes of frequency tripling. The second part is system disturbances analysisand suppression measures. And the third part is experimental research on highefficiency frequency tripling system.Optimized design of frequency tripling is the basis of achieving efficient andstable output light. In this dissertation, by the derivation of coupled wave equations,theoretical model is established. Based on this model, efficient frequency triplingsystem is designed, including algebraic comparision of two schemes, optimizationof crystals and the control methods under different user needs. Ultimately II/IIpolarization mismatch scheme is adopted and thicknesses of crystals are both14mm.By controlling the entire module with deflecting, pitching and rolling, the angles ofdoubler, tripler and polarization are adjusted accurately.System disturbances analysis is an important prerequisite for operation stablity.In this thesis, electric-field amplitude ripple caused by noise, transmissiondiffraction modulation, temperature perturbation, electric-field time waveform,distortion of crystal and mechanical vibration are analyzed. The result shows thatwhen the noise modulation depth is shallow, it has little influence on the system.When the modulation depth increaces to0.07, the frequency tripling efficiency willdrop more than10%. For other disturbances, the corresponding suppressionschemes are put forward.The experimental reseach mainly includes system testing, offline experiment,transmission of offline datum and online experiment. Firstly, the performances oftemperature and humidity controlling system, electric control system, mechanicalsystem are tested. Then the offline and online experiments are carried out and theoutput light with the wavelength of351nm is obtained, whose frequency triplingefficiency is33%. Finally, based on the existential problems, measures to improvesystem performance are raised.