Photoelectron spectra of photoionization of hydrogen atom subjected to super-intense laser pulses with various chirped parameters ξ = 0, 1, 2, and 3. In each case, we have fixed the peak intensity with I₀ = 5 ×10¹⁷ W/cm², and the pulse length as τ = 6 fs (a) and 30 fs (b). The bottom panels are the corresponding power spectral profiles of laser pulses. The laser frequency is the same as previous figures.