Emission From Silicon As A Real-Time Figure Of Merit For Laser-Induced Periodic Surface Structure Formation

In this work femtosecond laser treatment of crystalline silicon was performed with the aim of producing laser-induced periodic surface structures (LIPSSs), and emission from the processing area was measured. Broad photoluminescence (PL) of the oxidized silicon, second-harmonic generation (SHG) of the laser radiation on the structured surface and sharp emission lines (ELs) of the ablated silicon atoms were detected. The ratio of intensities of SHG to PL (or SHG to EL) is suggested as a real-time figure of merit for LIPSS formation. Diffraction patterns of white light on the produced LIPSS confirm this suggestion.