Polarization-dependent near-IR ultrashort-pulse laser ablation of natural diamond surfaces

Single-shot surface ablation of (001) and (111) oriented natural diamond plates was performed by tightly focused (numerical aperture NA = 0.65) 1030 nm 0.3-picosecond laser pulses with variable polarization azimuth. Surface craters were characterized by scanning electron microscopy in terms of characteristic ablation 1/e-radii and threshold fluences. Azimuthal polar dependences of the radii and threshold fluences exhibit distinct patterns, coinciding with specific crystallographic directions and corresponding bandgap widths in the Brillouin zone, and implying multiphoton-excitation seeding process. For comparison, anti-correlating azimuthal dependences were also observed in the bulk diamond for side-viewed A-band photoluminescence yield and forward non-linear transmittance.