Experimental Study Of High Harmonic Generation From Inert Gas Using Femtosecond Laser

Technological advances in femtosecond laser have permitted the laser with high peak intensities. The light-matter interactions have been accounted into the strong- field physics. The high harmonic generation(HHG) is one of the phenomenons in the strong-field physics. It can be used as the solution of attosecond pulse generation and coherent X ray emission. In this paper, the high-order harmonic characteristics in theories and experiments were investigated.The experimental system's designation and building were introduced which was used to detect and diagnose the harmonics. The difficult point is the designation of light path in the diagnosing cavity, because we must consider the harmonics collection efficiency. And finished the analysis of the harmonic spectrum.In the section of experiments, the parameters were studied which would affect the process of HHG, including laser power density, phase-matching. 19~32th order harmonic radiation was observed within gas air and Ar. The affect of different gas pressure to HHG was analysed. The experiment datas showed that the harmonic growed with the gas pressure until a optimal pressure. And after the optimal pressure, the harmonic decreased. For 27th harmonic, the optimal pressure was 110Torr. And different order harmonic had different optimal pressure. It was because of the affect of the gas pressure to phase-matching in the progress of HHG. The focusing position was analysed. It can be attributed to the self-guided effect.