Fig. 1. Curves for (a) α_opt(B), (b) F_τ(B), and (c) F_i(B) for α = α_opt for KDP (blue) and silica (red): FTL pulse at k₃ ≠ 0 (solid curves) and k₃ = 0 (dashed curves); non-Gaussian FTL pulse, the spectrum and autocorrelation function of which are presented in Figure 3(a) (dotted curves). FTL, Fourier-transform-limited.

Fig. 2. Schematic of the experiment. CM, chirped mirror; GW, small-aperture glass wedge; AC, autocorrelator; S, spectrometer.

Fig. 3. Measured input (blue) and output (red) spectra and ACF for two typical shots: (a) B = 13, τ_in = 67 fs, τ_out = 10.9 fs and (b) B = 14, τ_in = 57 fs, τ_out = 10.1 fs.

Fig. 4. Experimental minimal compressed pulse duration τ_out for KDP (L = 4 mm), silica (L = 5 mm), and silica (L = 3 mm^[15,20]) for two ranges of B values. The curves are plotted to make the figure more illustrative.

Fig. 5. Output pulse duration τ_out (blue) and pulse compression factor F_τ = τ_in/τ_out (red) at α = −200 fs²; τ_in = 55, …, 67 fs.