Fig. 1. Scanning electron micrographs of the RAR metasurface without laser exposure, showing (a) side view at 60° from normal and (b) top view. Note that the bulbous appearance of the tips of the structures is an artifact of the platinum coating process required for imaging and that the actual features are more pointed.

Fig. 2. SEM images of an example site formed by 1.4-ns pulse duration, at 24 J/cm². (a) Overview of the entire damage site, (b) zoom-in as indicated in yellow, (c) further zoom-in as indicated in the white dashed region showing the modified nanostructure, as compared with (d) the pristine location on the same scale. (e) Further zoom-in, as indicated in green, showing elongated features in the crater.

Fig. 3. Images of a damage site formed by 10-ps pulse duration, at 2.6 J/cm². (a) DIC microscope image overview, (b) SE-SEM image of a region showing two types of damages, which are further magnified to show the (c) larger type in the solid-line region and (d) smaller type in the dashed line region. Both (c) and (d) are BSE-SEM images.

Fig. 4. Images of a damage site formed by 0.8-ps pulse duration, at 2.4 J/cm². (a) DIC image overview, (b) SE-SEM image near the center of the site and (c) BSE-SEM image of the solid-line region, magnifying the shallow damage pits.

Fig. 5. Images of a damage site formed by 100 pulses of 20-fs duration, at 1.1 J/cm², collected via (a) in situ dark-field microscopy, (b) DIC microscopy and (c) SEM. The rectangle in (a) corresponds to the imaged region of (b) and (c), indicating detected modifications not observed in DIC and SEM images.

Fig. 6. Fluorescence microscopy images of 20-fs, 100-on-1 damage sites on an RAR silica sample, organized by femtosecond-laser fluence (horizontal) and excitation wavelength of the microscope (vertical). The fluorescence signal was integrated for wavelengths of more than 400 nm.

Fig. 7. Experimental LIDT results. (a) All measured LIDT values as a function of pulse duration. (b) Ratio of LIDT values from multipulse tests (R-on-1 or 100-on-1) divided by those of single-pulse tests (1-on-1). (c) Ratio of LIDT values of the RAR samples divided by those of the untextured samples. Additional data points for 20-fs duration correspond to an additional sample.

Fig. 8. Simulated metasurface shape and example cross-sectional color maps of EFI distribution. (a) Perspective view of the structure. (b) Example side-view cross-section, with the top (black) showing the structure and the bottom (color) mapping the EFI, with laser polarization directed into the page. (c) Example top-view cross-section mapping the EFI at a height in the middle of the nanopillars, with laser polarization oriented vertically. Black indicates the location of air/vacuum.