## 2 Materials and Methods  
The experiments were carried out with a Ti:Sapphire laser system (Quantronix) delivering 60 fs pulses with an energy up to 3.5 mJ (85% of which reaches the target) at the central wavelength of 804 nm and with a 1 kHz repetition rate [22]. The experimental setup is shown schematically in Figure 1a. The laser beam was focused onto the target by a 60\({}^{\circ}\) off-axis parabolic mirror (F/1.5) to a 6.8 um spot (FWHM), providing a peak intensity of 5 \(\times\) 10\({}^{16}\) W/cm\({}^{2}\). The measured nanosecond and picosecond laser pulse contrast was about 10\({}^{-5}\)-10\({}^{-4}\), as determined by the third-order cross-correlation technique. The corresponding fluence of \(<\)0.3 J/cm\({}^{2}\) is weak enough to ensure that no pre-plasma can be generated. Therefore, a sharp plasma density gradient was guaranteed. The corresponding Rayleigh length of \(\approx\)65 um is significantly longer than the length of nanowires (NWs). The focal spot was characterized with a standard microscope objective (\(\times\)20) and a change-coupled device (CCD). The polarization of the laser beam at the target was controlled by a half-wave plate. The incident angle of the laser pulse on the target was fixed at about 40\({}^{\circ}\). The resulting laser pulse intensity on the target surface corresponds to a normalized vector potential \(a_{0}=eE/m_{0}\omega c\cong 0.15\ll 1\), implying non-relativistic interaction. The targets were mounted on an XYZ-translation stage, allowing a new beam position on the target for each laser pulse and change of the target's position along the focus. The experiment was performed with both nanostructured and bulk zinc oxide (ZnO) targets. This dielectric material is transparent for incident laser radiation at 800 nm, which can promote a volume ionization and extensive exposure to the high-intensity laser field. Wurtzite, single crystalline ZnO nanowire (NW) batches were synthesized using a thermal transport technique within horizontal tube furnaces. We used two different types of nanostructured targets. The first type was an ordered array of NWs consisting of parallel, up-standing NWs perpendicular to the substrate (Figure 1b). The second set of samples contained disordered arrays revealing a batch of NWs chaotically arranged along the sample surface (Figure 1c). The different morphologies of the structures were achieved by carefully adjusting the growth conditions [23; 24]. Briefly, the disordered nanowire samples were synthesized via the vapor-liquid-solid (VLS) mechanism [25] on Si chips covered beforehand with a 10 nm gold layer to act as liquid catalyst droplets during growth. The ordered NW samples were grown self-catalytically using the vapor-solid (VS) approach on a 500 \(\upmu\)m thick Si substrate covered with a 500 nm Al-doped ZnO seed layer [26]. The NWs were typically 5 \(\upmu\)m and 15 \(\upmu\)m long for ordered and disordered NW samples, respectively, and had a diameter of about 100-200 nm. Since the measurements were done for different polarizations of the laser beam, it is important to explain the direction of polarization with respect to the target morphology (Figure 2). S- and p-polarization are used to refer to the laser pulses with an electric field perpendicular or parallel to the \(kn\)-plane (the plane of incidence), respectively. Along with their orientation and a finite angle of incidence, p-polarized laser pulses always have a field component \(\overrightarrow{E_{p}n}\) normal to the target surface. Reference measurements were carried out with flat, 0.5 \(\upmu\)m thick polished ZnO bulk substrates (CrysTec GmbH), which were oriented along the [0001] direction. The experiments were conducted in a single-shot regime. The area of the target surface was large enough to support over 200 laser pulses for statistical characterization of the results (Figure 3a,b). It can be clearly seen with an optical microscope that the damage spots are nicely separated (Figure 3c).