Fabrication of novel structures on silicon with femtosecond laser pulses

In this study, the fabrication of novel micro/nano structures were induced on silicon surfaces us-ing radially and azimuthally polarized femtosecond laser, with a ~120 fs pulse duration, an 800 nm wavelength, and a 1 kHz repetition rate. Results showed that, as the laser fluence approached the ab-lation threshold of the silicon, nanostructures with a period of approximately 600~700 nm were formed at the low laser fluence region (0.7~0.8 J/cm²), and their orientations were perpendicular to the laser polarization. However, as the laser fluence increased (0.9~1.1 J/cm²), microstructures with a period of approximately 2~3 μm were formed, and their orientation were parallel to the laser polarization.