Femtosecond laser processing of silver-containing glass with optical vortex beams

We report on vortex-assisted femtosecond direct laser writing (DLW) in silver-containing phosphate glasses with complex light fields endowed with optical phase singularities. This allows us to engrave complex patterns showing sub-wavelength dimensions. The associated linear and nonlinear optical properties show remarkably correlated but distinct spatial distributions. The creation of a perennial buried electric field leads to an efficient electric- field induced second harmonic generation. The magnitude and distribution of such buried field is also considered to actively drive the pattern topology of the fluorescent silver clusters. Using DLW with phase and amplitude engineered beams, we demonstrate a promising approach to control both fluorescent and nonlinear responses below the diffraction limit