Morphogenesis of mesoscopic surface patterns formed in polarized two-photon etching of diamond

Abstract Two-photon etching of diamond surfaces is a novel technique for providing controlled removal of atomic layers and nano-patterning the surface. However, the details of the etching mechanism and pattern development are not well understood so that the full capability of the process is unclear. Here, a comprehensive investigation into the dynamics of nanopattern formation on the (100), (110) and (111) facets is reported as a function of polarization, for CVD and HPHT diamond, and for nanosecond and picosecond laser pulse durations. A diverse array of behaviour is observed including sub-wavelength scale structuring with morphologies characteristic of the facet and selected polarization. As etching proceeds, the anisotropies in the quantum photon-lattice interaction are imprinted on the emergent patterns on nano and mesoscopic scales. The sum of the results leads to rules for predicting pattern type, roughness and etch rate. We also argue that they support a mechanism for carbon ejection based on the photo-ejection of carbonyl groups from carbonyl-supporting surfaces, defects and atomic-level step edges. The results provide guidance for optically manipulating diamond surfaces and comprise a major step towards a complete model for the process to aid laser direct-write structuring of functional diamond surfaces.