Figure 2

(a) Optical microscopy image of the cross-section of the laser track with a pulse energy of 0.8 µJ in Xx configuration. (b) Raman spectra normalized to area for three different cases: pristine glass, head and bottom of the teardrop-shaped structure. (c) Mapping of the Raman intensity retrieved by integrating the full Raman intensity from 177 to 1580 cm⁻¹ without normalization. (d) Mapping of the ratio Band1/Band2 retrieved by integrating the normalized spectral region from 380 to 670 cm⁻¹ (Band1) and from 670 to 1000 cm⁻¹ (Band2). (e) Molecular oxygen distribution (peak at 1555 cm⁻¹). The laser writing parameters were 1030 nm, 10 µm/s, 100 kHz, 0.6 NA, 500 µm depth.