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 using 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 ablation 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/cm 2 ), and their orientations were perpendicular to the laser polarization. However, as the laser fluence increased (0.9~1.1 J/cm 2 ), microstructures with a period of approximately 2~3 m were formed, and their orientation were parallel to the laser polarization.