Figure 5
SEM images illustrating the structures formed on the silicon surface after irradiation with fs VV beams generated by three different q-plates for two different values of the optical retardation δ. The scale bar in the SEM images corresponds to 20 µm. Panels (a) and (b) show the case of q = 3/2 for δ = 1.51π and δ = 0.59π at a pulse energy E0 = 65 µJ. For this case, the lower panels (c) and (d) display the corresponding simulated far field intensity and SoP patterns of the corresponding VV beams. The scale bar, shown in panel (c), is 20 μm. Panels (e) and (f) illustrate the case of q = 2 for δ = 1.4π and δ = 0.61π at a pulse energy E0 = 55 µJ. Panels (g) and (h) report the case q = 5/2 for δ = 1.28π and δ = 0.61π at a pulse energy E0 = 100 µJ. In all cases, the number of pulses is N = 200.
