Single crystal diamond micro-disk resonators by focused ion beam milling

Abstract

We report on single crystal diamond micro-disk resonators fabricated in bulk chemical vapor deposition diamond plates (3 mm × 3 mm × 0.15 mm) using a combination of deep reactive ion etching and Focused Ion Beam (FIB) milling. The resulting structures are micro-disks of few μm in diameter and less than 1 μm thick, supported by a square or diamond section pillar resulting from the multi-directional milling. Thin aluminum and chromium layers are used to ground the substrate, limit the ion implantation, and prevent edge rounding and roughening. FIB damage is then removed by a combination of hydrofluoric acid etching, oxygen plasma cleaning, and annealing at 500 °C for 4 h in air. We experimentally characterize the optical behavior of the devices by probing the transmission of a tapered fiber evanescently coupled to the micro-disk, revealing multiple resonances with a quality factor up to 5700 in the S- and C-band.