(Aug 1st) Micro- and Nanostructuring of Single Crystal Diamond for Photonic Applications

Single Crystal Diamond has emerged as a prime material for emerging integrated photonic applications. While substrates have been made available in recent years by several commercial suppliers in high crystal quality and suitable form factors as polished plates, shaping photonic structures remains challenging. In this talk, I will discuss a set of experimental techniques recently developed in our group to prepare and structure single crystal diamond substrates at the micro- and nanoscale for emerging photonic applications. Surface preparation is achieved by Ion Beam Etching, effectively removing scratches and sub-surface damage introduced by mechanical polishing. We employ lithography techniques on the substrate surface for patterning and Reactive Ion Etching using oxygen based plasma chemistries for pattern transfer into the diamond. By varying the platen bias power, the etch rate and directionality can be adjusted. While a high platen bias power enables Deep Reactive Ion Etching for micro-optical components, removing the platen bias entirely, we observe an effective etch rate dependence on the crystalline plane orientation. We have demonstrated, that the resulting anisotropic etch process is suitable for fabrication of diffraction gratings with precisely defined angles and smooth surfaces along the (111) crystal planes. Finally, we will introduce our multidirectional Focused Ion Beam Etching technique to fabricate freestanding optical disk resonators. With appropriate metal coatings and annealing procedures, surface damage and ion implantation can be minimized, yielding optical resonators with optical Q-factors up to 5’700 at a wavelength of 1.5 µm. The experimental demonstration of the fabricated diffractive optical elements and micro-disk resonators underline the suitability of the employed techniques for manufacturing of photonic devices in monocrystalline diamond.