Universal strategies for enhancing the laser energy loading capability of pulse compression gratings

The pulse compressor has evolved to be a core module of 100 Petawatt (PW) or Exawatt laser facilities; however, the diffraction efficiency bandwidth, laser-induced damage threshold (LIDT), and aperture of its currently deployed gratings strongly restrict the ultra-intense and ultrashort pulse compression. Maximizing the energy-loading capability of gratings is a worldwide challenge in the high-peak-power laser field. Here, for 10’s femtosecond-PW pulse compression, an ultra-broadband gold grating was developed to dramatically broaden the high diffraction efficiency bandwidth from 100–200 nm to 400 nm. Moreover, a core mechanism was elucidated whereby the high diffraction efficiency combined with the deep penetration effect of electrons under high-energy laser irradiation can tap the LIDT potential of metal grating. Accordingly, the mixed metal grating was invented and demonstrated experimentally with superior performance in terms of diffraction efficiency bandwidth and LIDT compared with normal gold gratings. In addition, for picosecond-PW pulse compression, a multilayer dielectric grating (MDG) design paradigm was proposed. Importantly, TM-polarized MDGs had the superiority of a high LIDT owing to the low electric field intensity. Furthermore, a novel grating with a LIDT 3.5 times higher than the conventional gratings installed in NIF-ARC and SG-II was obtained by taking advantage of TM polarization and a small incident angle. These results make a pioneering technical reserve to facilitate future 100 PW-class ultrafast laser systems.