Two-pass full-tiled grating compressor with real-time monitoring and control for XG-III petawatt-class laser facility

A two-pass, full-tiled grating compressor with a unique feedback control system for precise alignment was realized in an XG-III petawatt-class laser facility, based on the chirped-pulse amplification (CPA) technique. Far-field images of both 0th order and -1st order diffraction light of a tiled grating assembly (TGA) were recorded using a CCD camera, by which the tiling errors of the TGA can be identified and corrected in real-time without disturbing the main beam. A final compressed pulse of 615 fs (FWHM) with a focal spot about 1.1 times the diffraction limited (DL) size was achieved.