Measurement and compensation for the chromatic aberration of SG-II 5PW laser system

Pulse time delay (PTD) and defocus are mainly introduced by transmitted-based large-aperture beam expander systems in ultrashort high power laser systems due to chromatic aberration, which can significantly reduce the focal-spot intensity by spatially enlarge the spot size as well as temporally distort the pulse profile. In this paper we investigate the chromatic aberration and measure how it deteriorate the focal spot size in SG-II 5PW ultrashort laser system. In addition, we propose and design a simple chromatic aberration pre-compensation scheme based on combination of aspherical lens and spherical mirrors. The simulation results indicate that both PTD and defocus dispersion can nearly be fully compensated by applying this compensation scheme with proper alignment in the system without introducing other kinds of wave-front aberrations.