Improvement of focusing performance for a multi-petawatt OPCPA laser facility

• Published in: Laser physics 2018-12, Vol.28 (12), p.125301
• Main Authors: Zhou, Kainan, Huang, Xiaojun, Zeng, Xiaoming, Xie, Na, Zuo, Yanlei, Guo, Yi, Jiang, Dongbin, Dai, Wanjun, Xue, Qiao, Huang, Wanqing, Li, Ende, Wei, Ling, Sun, Li, Wang, Xiao, Su, Jingqin
• Format: Article
• Language: English
• Subjects: adaptive optics; parametric amplifiers; ultrashort pulse laser
• ISSN: 1054-660X; 1555-6611
• DOI: 10.1088/1555-6611/aae0db

In the paper, we demonstrate improvement of the focused intensity for a multi-petawatt optical parametric chirped-pulse amplification laser facility by several methods. An adaptive optics system with a large-size deformable mirror is employed and it applies a closed-loop correction method based on detection of the on-target focal spot rather than wavefront. In addition, a pair of achromatic lenses is designed and utilized to compensate chromatic and spherical aberrations of the laser system. Moreover, the additional dynamic aberrations introduced by 3-stage optical parametric amplifiers are investigated experimentally. After optimization, the focal spot size (full width at half maximum, FWHM) is 3.3 µm  ×  4.0 µm in x-axis and y-axis directions and the enclosed energy in FWHM is 28% when an on-axis parabolic mirror with a focal length of 800 mm is used. The focused intensity of ~4  ×  1021 W cm−2 has been achieved for a 1.6 PW shot. The laser intensity is expected to be 1022 W cm−2 or higher for 4.9 PW peak power.