| Optical system has a technologically advanced, full functions, indicators of high, programmable control, splitting reliable, flexible and stable fiber-optic transmission, system stable and reliable characteristics, so it has a good prospect in laser-driven inertial confinement fusion. Particularly for large-scale laser inertial confinement fusion devices, all-fiber front-end system as a seed source, has played a significant role.Sinusoidal phase modulation pulse is generally used as a seed source on high-power laser device at home and abroad. The one hand it can provide some optical bandwidth to suppress the transient stimulated Brillouin scattering in large diameter optics; the other hand, it can provide periodic chirp over time to meet the experimental requirements for beam smoothing. The article systematic studies the problems encountered in high power laser facility using this technical line, particularly in the front-end system, including the group velocity dispersion, polarization mode dispersion, gain narrowing and optical devices with weak etalon effects on the FM-AM effects. In addition, the new generation of high-power laser system required to further improve output energy of the front-end to reduce the pressure on the follow-up system, so the theory of the optical fiber amplifier is the main basis for front-end optical systems. Finally, as a forward-looking pulse shaping techniques, the theoretical study of chirped pulse stacking scheme can provide a new way to produce the seed source for high-power laser facility.The main constents of this paper:â… . Based on the theory of the pulse transimission in the optical fiber, respectively, the effects of group velocity dispersion, polarization mode dispersion, self phase modulation, stimulated Brillouin scattering on optical pulse propagation were theoretical analyzed, and the effects of group velocity dispersion, polarization mode dispersion and polarization stability of polarization-mataining fiber on frequency modulated pulse were experimentally studied.â…¡. First, we theoretically analyzed the deficiency of the existing optical fiber amplifier and broadband fiber amplifier rate equation model, then broadband amplifier model that contains the inversion,dispersion and nonlinear effect, and the calculation method were put forward on this basis. Next, some boundary conditions of the amplifier were discussed. On this basis, the model of stimulated Brillouin scattering in fiber amplifier was proposed, and the corresponding experiment was carried out. Finally, introduced a highly efficient high-power fiber laser systems, and the experimental results were theoretically discussed, the experimental results agree well with the theoretical simulation.â…¢. First, introduced the principle of sinusoidal frequency modulation and pulse generation methods, the FM-AM effect encountered in the front-end system of high-power laser facility using sinusoidal frequency pulse technology is theoretically analyzed, and the effect of wave plate,gain narrowing and other issues were theoretically and experimentally studied. Finally, the principal means of compensation to the FM-AM effect were proposed, and each method was theoretically analyzed, then the advantages and disadvantages of each method were summarized.â…£. The shaping method of chirped pulse stacking was studied, and the characteristics of chirped pulse stacking were theoretically analyzed, which contains the effect of the dispersion, self-phase modulation and amplification effect on the stacked pulses. The stacked pulse spectrum,arbitrary shaping ability and the time modulation impact on the high power laser facility were experimentally studied. Then a method of super-Gaussian chirped stacking technique was proposed, and the time domain and frequency domain,transmission and amplification characteristic of the super-Gaussian stacking pulses were analyzed. Finally, the other relevant application was proposed.The main innovation of this paper are as follows:â… . The problems encounterd during the sinusoidal phase modulation pulse transmission in the front-end system of high power laser facility are systematically discussed, and the effects of the group velocity dispersion, polarization mode dispersion on the phase modulation of pulse waveform were theoretically and experimentally studied.â…¡. The broadband fiber amplifier model was proposed, which contains inversion distribution,dispersion and nonlinear effect, and the model can more accurately describe the high-power fiber amplifier. There was no approximation for the gain function, and the actual gain distribution was used in simulation, and the model has a good agreement with the experiment results. Then launched a highly efficient high-power fiber laser system, and experimental results with the same conditions in the domestic is in the leading level.â…¢. For the transient stimulated Brillouin scattering observed in single-frequency fiber amplifier experiment, the model for transient stimulated Brillouin scattering (SBS) of high-power fiber amplifier was proposed. Then the model and its characteristics were preliminary theoretical study, experimental and theoretical results show that the transient SBS will cause a single-frequency pulse waveform distortion in the optical fiber amplifier, and limiting the amplifier output.â…£. The FM-AM effect in high power laser facility was preliminary systematic studied, especially for the weak etalon effect of waveplate and other optics in high-power laser facility, experiment and theoritcal study were carried out, and theoretical and experimental research results agree well. Beacause of many complicated factors could result in FM-AM effect in high power laser facility, the method of liquid crystal spatial light modulator used to compensate arbitrary amplitude and phase transmission function was proposed.â…¤. For the time modulation existed in the chirped Gaussian stacked pulse, the technology of super-Gaussian linearly chirped pulse stacking was proposed, and the corresponding theoretical study was carried out.
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