"By adding a 2×2 coherently tiled titanium:sapphire high-energy laser amplifier in China's SULF or EU's ELI-NP, the current 10-petawatt can be further increased to 40-petawatt and the focused peak intensity can be increased by nearly 10 times or more.

The method promises to enhance the experimental capability of ultra-intense ultrashort lasers for strong-field laser physics.

After reaching a world record of 10 PW, the peak power development of the titanium-sapphire (Ti:sapphire) PW ultraintense lasers has hit a bottleneck, and it seems to be difficult to continue increasing due to the difficulty of manufacturing larger Ti:sapphire crystals and the limitation of parasitic lasing that can consume stored pump energy. Unlike coherent beam combining, coherent Ti:sapphire tiling is a viable solution for expanding Ti:sapphire crystal sizes, truncating transverse amplified spontaneous emission, suppressing parasitic lasing, and, importantly, not requiring complex space-time tiling control. A theoretical analysis of the above features and an experimental demonstration of high-quality laser amplification are reported. The results show that the addition of a 2 × 2 tiled Ti:sapphire amplifier to today's 10 PW ultraintense laser is a viable technique to break the 10 PW limit and directly increase the highest peak power recorded by a factor of 4, further approaching the exawatt class.

Femtosecond petawatt (fs-PW) ultraintense lasers, which are produced by chirped-pulse amplification (CPA), have opened and accelerated the research and development of plasma physics, particle physics, astrophysics, nuclear physics, etc…

Japan developed the first fs-PW Ti:sapphire ultraintense laser in 2003. Korea completed a 4.2 PW Ti:sapphire ultraintense laser in 2017. China and Europe accomplished two 10 PW (around 22 fs and 220 J) Ti:sapphire ultraintense lasers [i.e., Shanghai Super-intense Ultrafast Laser Facility (SULF) and Extreme Light Infrastructure – Nuclear Physics (ELI-NP)] in 2018 and 2020.