Fig. 1. Comparison of the spatial chirp distortion of the amplified signal calculated for (a), (c) saturated OPCPA based on a 5-mm-thick YCOB crystal and (b), (d) saturated QPCPA based on a 15-mm-thick Sm³⁺:YCOB crystal. (a), (b) Intensity profiles in the spatial and spectral domain. (c), (d) Signal spectra at the beam center (x = 0) and beam edge (x = W₀).

Fig. 2. Comparison of the SR and spatiotemporal performance of OPCPA and QPCPA outputs. (a), (b) The evolutions of SR and signal efficiency with the crystal length. (c), (d) The compressed signal distribution in space and time. (e), (f) Three compressed signal pulses sampled at x = 0, 0.6W₀ and W₀, for OPCPA and QPCPA, respectively. Insets in (a) and (b) depict the spatiotemporal profiles of the focused signal, which were calculated with the crystal lengths of 5 and 15 mm, respectively. Simulation parameters were the same as those listed in Figure 1.

Fig. 3. The dependence of SR performance on the idler absorption coefficient, seed bandwidth and pump intensity. (a) Calculated SR versus idler absorption coefficient for three seed bandwidths of 50, 100 and 200 nm under a fixed pump intensity of 80 GW/cm². (b) Calculated SR versus pump intensity for three idler absorption coefficients of 0.3, 1, and 2 cm^–1 under a fixed seed bandwidth of 100 nm.

Fig. 4. Characterization of the spatiotemporal performance of QPCPA based on a real Sm³⁺:YCOB crystal. (a) The absorption spectrum of a real Sm³⁺:YCOB crystal, where the gray area of the spectrum is adopted in the simulation of QPCPA. (b) The evolutions of SR and signal efficiency with the crystal length under the condition of nonuniform idler absorption. The inset shows the spatiotemporal distribution of the compressed signal, which was calculated with the crystal length of 15 mm.