Fig. 1. MELBA spatial profile on the fused silica sample.

Fig. 2. (a) Examples of power profiles measured with a 33 GHz-bandwidth oscilloscope and photodiode. From left to right: FIT reference and 2, 10 and 30 GHz pulses. The modulation index is approximately equal to for modulated pulses. Power profiles are normalized so that the average power is equal to 1. (b) The amplitude of the Fourier transform for each power profile shown in (a).

Fig. 3. (a) Damage laws for the FIT reference pulse and three 2 GHz pulses of different modulation indices. (b) Damage laws for the FIT reference case, two 10 GHz pulses with different modulation indices and a 30 GHz pulse.

Fig. 4. Damage laws determined on a fused silica sample polished by another vendor (reference FIT pulse, 2 GHz modulation and 10 GHz modulation).

Fig. 5. Histogram of the damage site diameter for the reference unmodulated pulse (no mod.) and the two amplitude modulations at 2 and 10 GHz. Data were analyzed from the results of the experiment presented in Figure 4.

Fig. 6. Outline of the modeling of subsurface micro-cracks. The crack is modeled by a 100 nm void surrounded by amorphous silica. Absorption of the UV laser at the SiO₂/void interface is represented by an arbitrary absorbing defect layer.

Fig. 7. Radial stress and temperature output of the code with respect to time and the 1D parameter .

Fig. 8. Determination of the laser-induced damage threshold (LIDT) from a damage law, given a damage density threshold defined at nb/cm.

Fig. 9. Evolution of radial stress with respect to laser fluence for different temporal modulations: 2 GHz with or , 10 GHz with and 30 GHz with . Arrows point to the LIDT obtained for the reference without modulation (no mod.) as well as modulated pulses with .

Fig. 10. Evolution of the maximal temperature reached inside the micro-crack with respect to time for the unmodulated reference pulse and two modulated pulses at 2 and 10 GHz ().