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Using comb laser pulses synchronized with the main pulse output by large laser facility as time fiducial to scale the reaction process between high power laser pulse and target is very important for the realization of precise measurement and simulation in the intense field experiment. We demonstrate a fiber multiharmonic time fiducial laser pulse generation system using optic-electric modulation and optical pulse stacking. A unit optical pulse with a width of 150 ps generated by modulation was stacked in a fiber stacker to form a 1053 nm comb pulse. The pulse was then amplified and frequency-converted to generate green (527 nm) and UV (351 nm) fiducials. The system can stably provide Shenguang-Ⅲ prototype facility with multi-frequency laser time fiducials which is essential for the precise physical experiment. In addition, the system is highly adaptive since it can generate fiducial signals with variable pulse intervals and amplitudes flexibly according to the requirements of different physical experiments.

Based on the energy-level structure of quasi-three-level Yb ion，an amplified spontaneous emission model in pumping process is set up. The stored energy density distribution and the energy that can be extracted in Yb：YAG crystal are calculated. Our calculation，which is based on the laser rate equations and the theory of anglular spectrum propagation，can simulate time-resolved evolution of the spatial intensity distribution and M2 factor of the laser pulses. At the same time，an experiment in laser diode-pumped Q-switched rep-rated Yb：YAG disk laser was performed. This model was proved to be correct by comparing the results of the experiment and calculation，which will be helpful in designing active Q-switched solid laser.

Based on the energy-level structure of quasi-three-level Yb ion, an amplified spontaneous emission（ASE） model in pumping process is set up. The stored energy density distribution and the energy that can be extracted in Yb:YAG crystal are calculated. The effect of ASE on energy-storage is investigated specifically, which includes the aperture, doping concentration and thickness, and working temperature of the gain medium. This paper gives an optimizing design of a pulsed energy-storage rep-rated Yb:YAG disk laser amplifier, which will be helpful in designing high-energy diode-pumped solid-state lasers based on Yb-doped materials.

We observed the characteristics of high energy nanosecond chirped pulse by spectral-resolved streak camera，which works well with energetic chirped pulse of nanosecond pulse duration. At the same time，it can monitor the alignment of grating compressor. The measurement results show that the pulse generated by PW demonstration facility is linearly chirped，verifying the compressibility of amplified nanosecond pulse.

The method of Power spectra density was introduced to estimate the quality of a high intensity laser beam, and the near field of the self-focusing laser beam was analyzed. We obtained a certain ΔB restriction of the laser beam.The results of numerical simulations were coincident with the experimental data very well .