Study On Kerr Effect In ICF Solid-state Laser

Nowadays, human beings face the crisis of lacking energy sources. However, the energy generating from Inertial Confinement Fusion (ICF) can solve this problem effectively. ICF has been driven by the high-power solid-state laser system, including the propagation and the harmonic generation. In this process, the third-order nonlinear interaction is one of the important reasons that degraded the quality of beams, and reduced the efficiency of the harmonic generation. Furthermore, they can even cause the damage and destroy of optical components. In this dissertation, the third-order nonlinear interaction in ICF solid-state laser has been studied, and its character and influence in propagation and in third harmonic generation have been investigated as well.In the beginning, we investigated the action and the restraining means of the third-order nonlinear interactions in the propagation. We used a negative nonlinear refractive index (n₂<0) material as the compensating medium, and compared with the different compensation methods. The results indicate that compensation can decrease B integral along the beam direction in a nonlinear medium, and can restrain the self-focusing of beams greatly. Compensation can also avoid the nonlinear increase on the edges of super-Gaussian beams effectively. The numeric calculation indicates that the compensation after nonlinear medium is the ideal compensating method.Furthermore, we studied the characteristic of the third-order nonlinear (TON) interaction in the third harmonic generation. On the basis of the coupled-modeequations, taking into account the effects of the third-order nonlinear interaction, transverse walk-off and diffraction, especially the effects of TON interactions on the frequency conversion and the phase matching condition have been discussed. A split-step algorithm based on the Fast Fourier Transform and a Runge-Kutta integrator was used. The results have shown that the TON interactions decrease the tripling efficiencies evidently, and increase of the modulate depth of the output intensity of 3 w radiation. However, the method of adjusting the angular detuning can avoid the effects of third-order nonlinear effectively.In addition, the beam quality of 3 oo radiation in the third harmonic generation has been studied. The effects of the amplitude modulation and the phase perturbation have been especially attended in this paper.