Impact of beam clipping in full-aperture grating compressors on the focal intensity contrast ratio

An analytical expression for intensity at the focal point for a full-aperture compressor of arbitrary configuration has been derived. At small times, the intensity contrast ratio (ICR)—the focal intensity normalized to its maximum—does not depend on clipping and is determined exclusively by the shape of an undistorted pulse spectrum. At large times, contrariwise, the ICR does not depend on the spectrum shape and is determined by clipping. In the latter case, the ICR is proportional to the second power of the group velocity dispersion of the compressor and is inversely proportional to the second power of the grating length and the pulse bandwidth as well as the fourth power of time. For the compressors proposed for the Exawatt Center for Extreme Light Studies (XCELS) and Station of Extreme Light (SEL-100 PW) projects, the ICR is 10 −10 …10 −9 at t ≈0.7ps, which is sufficient for most experiments.