Figure 3.

Left: Optical absorbance spectra of S-doped silica matrix: (a) non-irradiated area, (b) femtosecond laser irradiated area with 40 mW. Right: (c) PL spectrum of a non-irradiated area under excitation at 351 nm, (d) PL spectrum of the irradiated area under excitation at 351 nm, (e) PL spectrum of a non-irradiated area under excitation at 514.5 nm and (f) PL spectrum of the irradiated area under excitation at 514.5 nm.