Figure 6
SEM images of the silicon surface after irradiation with N = 200 fs VV pulses generated by four different q-plates; the topological charge, q, and optical retardation, δ, are indicated on the top of each image. The scale bars in the images correspond to 20 µm. The structures are produced at a laser pulse energy of: (a) 40 µJ, (b) 65 µJ, (c) 55 µJ, and (d) 100 µJ, respectively. The lower panels display the spatial maps of the fluence and SoP of the corresponding VV beam. The scale bar, shown in lower left map, is 20 μm.
