Extended Data Fig. 4: Laser picoscopy in CaF₂.

a, Intensity yields of representative harmonics (N = 9, 11 and 13) in CaF₂ measured as a function of the crystal rotation angle with respect to the c axis and for three representative driving field strengths (F₀ = 0.58, 0.65 and 0.7 V Å⁻¹). b, c, Intensity yields (black dots) of harmonics versus field strengths measured along the [110] (b) and [100] (c) axes of the crystal. The red and blue curves are the fitting of the intensity yields according to equation (18) or equation (3). Error bars in a–c indicate the standard deviation of the mean value from three measurements acquired under identical conditions. d, e, Retrieved amplitudes \({\tilde{V}}_{{k}_{{\rm{l}}}}\,\) and their relative phases (0 rad in blue and π rad in red) along the [110] (d) and [100] (e) axes of the crystal.