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, ‡}

Output power spectra of the input pulses passing through concentric phase mask of different duty cycles: (a) n = 0, (b) n = 0.4, (c) n = 0.5, (d) n = 0.6, and (e) n = 0.8.