Energetic few-cycle pulse compression in gas-filled hollow core fiber with concentric phase mask

Zhao Yu^{1, 2}, Huang Zhi-Yuan^{1, 2}, Zhao Rui-Rui^{1, 2}, Wang Ding^{1, †}, Leng Yu-Xin^{1, ‡}

Normalized spatial intensity profiles of compressed pulses: (a) compressed pulses without concentric phase mask and (b)–(e) compressed pulses with concentric phase mask under duty cycles of 0.4, 0.5, 0.6, and 0.8.