Improvement of the focusing ability by double deformable mirrors for 10-PW-level Ti: sapphire chirped pulse amplification laser system

Abstract

Double deformable mirrors (DMs) with different actuator densities are cascaded to optimize the wavefront aberrations to improve the focus intensity of the Shanghai super-intense ultrafast laser facility (SULF), which plans to generate 10 PW laser pulse. The beam aberrations near the focal spot are corrected from 0.556 um to 0.112 um in RMS by a 300-mm DM with a large stroke installed after the compressor. After then, it is further optimized to 0.041 um using a 130-mm DM with a high spatial resolution working after the main amplifier. The corrected beam is focused to 2.75 × 2.87 um² at the full width at half maximum (FWHM) with an f/2.5 off-axis parabolic mirror (OAP), which contains approximately 27.69% energy. A peak intensity of 2 × 10²² W/cm² is achieved at the output of 5.4 PW, and it could exceed 10²³ W/cm² in the SULF 10 PW laser facility using an f/1.8 OAP.