A new high power laser facility with 8 beams and maximum output energy of one beam 5kJ/3.4ns/3ω has been performed and operated since 2015. Combined together the existing facilities have constructed a multifunction experimental platform including multi-pulse width of ns, ps and fs and active probing beam, which is an effective tool for Inertial Confinement Fusion (ICF) and High Energy Density (HED) researches. In addition another peculiar high power laser prototype pushes 1ω maximum output energy to 16kJ in 5ns and 17.5kJ in 20ns in flat-in-time pulse, this system is based on large aperture four-pass main amplifier architecture with 310mm×310mm output beam aperture. Meanwhile the near field and far field have good quality spanning large energy scope by use of a wide range of technologies, such as reasonable overall design technique, the integrated front end, cleanness class control, nonlinear laser propagation control, wave-front adaptive optics and precision measurement. Based on this excellent backup, 3ω damage research project is planning to be implemented. To realize the above aims, the beam expanding scheme in final transport spatial filter could be adopted considering tradeoff between the efficient utilization of 1ω output and 3ω damage threshold. Besides for deeply dissecting conversion process for beam characteristic influence of 1ω beam, WCI (Wave-front Code Image) instrument with refined structure would be used to measure optical field with simultaneous high precision amplitude and phase information, and what’s more WCI can measure the 1ω, 2ω and 3ω optical field in the same time at same position, so we can analyze the 3ω beam quality evolution systematically, and ultimately to improve the 3ω limited output.
In a word, we need pay attention to some aspects contents with emphasis for future huger laser facility development. The first is to focus the new technology application. The second is to solve the matching problem between 1ω beam and the 3ω beam. The last is to build the whole effective design in order to improve efficiency and cost performance.
Amplified spontaneous emission (ASE) causes the decrease of the inverted population density and the nonuniformity of gain in slab amplifier for high power laser systems. In this paper, a three dimension model, based on the data in SG-II, in which the residual reflection in the cladding and the ASE process are taken into consideration, is built to analyze the space distribution and time evolution of small signal gain coefficient using Monte Carlo algorithm and ray tracing. This model has been verified by comparing with the experimental data. The traverse size of slab is 68.2cm×36.3cm, which is usually decided by the clear aperture and the manufacture. By means of the model, the impact of thickness, residual reflectivity and the stimulated cross section of neodymium glass to the ASE are analyzed in detail.