  A multistage smoothing multistep pulse compressor (MPC) based on a
single-pass single-grating-pair (SSGP) main compressor is proposed to simplify
the entire petawatt (PW) compressor. Only one grating pair with relatively long
distance is used to generate the same amount of spectral dispersion in the main
compressor compared with a four-grating main compressor. As the SSGP induces
the largest spatial dispersion, it can introduce the best beam-smoothing effect
to the laser beam on the last grating. When considering the diffraction loss of
only two gratings, the total compression efficiency of the SSGP main compressor
is even larger than that of a four-grating main compressor. Furthermore, the
spatiotemporal aberration induced by single-grating-pair can be compensated
effectively by using deformable mirrors, however it is difficult or complicated
to be well compensated in a four-grating compressor. Approximately 50-100 PW
laser pulses can be obtained using this SSGP-based multistage smoothing MPC
with a single laser beam
