Fig. 1. Filamentation traces in internal sapphire induced by picosecond laser irradiation

Fig. 2. Effects of picosecond laser peak power on (a) filamentation diameter and (b) filamentation length of sapphire

Fig. 3. Effect of laser focusing position on initial position of filamentation

Fig. 4. Effect of laser pulse number on filamentation diameter

Fig. 5. XRD spectra of (a) crude sapphire and (b) laser filamentation area

Fig. 6. Effect of overlap ratio of adjacent filamentation on roughness of sapphire cutting-surface

Fig. 7. Processing sample diagrams of sapphire. (a) Partial sapphire samples processed by laser filamentation cutting; (b) optical micrograph of the surface of crude sapphire edge (top) and cutting-surface of processed sample (bottom); (c) laser scanning confocal micrograph of cutting-surface of processed sample