Comparative Study on Grating Fabrication in Transparent Materials by TWIN-LIBWE and Ultrashort Pulsed Ablation Techniques

Two methods for micro-structuring of transparent dielectric were compared in this study: the two-beam interferometric laser-induced backside wet etching (TWIN-LIBWE) and the two beam interferometric ablation by ultrashort laser pulses. In TWIN-LIBWE we used the 4 th harmonic of Nd:YAG laser (=266 nm, FWHM =8 ns, fuence: 265-500 mJ/cm 2 ), while a Ti:Sapphire-based femtosecond system (=800 nm, FWHM =30 fs, pulse energy: 600-900 J) was used for direct ablation.