Pulse compression by an asymmetric four-grating compressor in the SEL-100 PW frontend

Laser induced damage of optics has made the compression gratings the shortest stave of PW lasers as manufacturing a grating with high enough damage threshold and big enough size remains particularly difficult. Asymmetric four-grating compressor (AFGC) based multistep pulse compressor method was proposed recently to alleviate the requirement of such gratings. It is further investigated experimentally with the SEL-100 PW frontend in this study. It is verified that the AFGC has the ability of spatial beam-smoothing resulting from the introduced spatial dispersion. Meanwhile, the spatial dispersion scarcely impacts on the pulse duration, temporal contrast and focal spot of the output beam. With the same size-limited compression gratings, the operational safety of the AFGC can be improved. By reducing the laser spatial intensity modulations (LSIM) from 2.0 to 1.3, the pulse energy capacity of the AFGC can increase more than 1.5 times without the need of additional optical elements or controlling.