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article i nfo Available online 19 March 2013 Gallium focused-ion beam milling is a commonly used technique for sculpting diamond at the nano and micro scale. However even at fluences insufficient to cause sputtering, implanted gallium causes modification of the optical properties of the diamond substrate. We implanted 30 keV gallium ions at fluences from 1×1 0 13 to 5 × 10 14 Ga/cm 2 and studied the effect on the optical properties via spectroscopic ellipsometry (SE), from 0.6 to 6.5 eV, obtaining the changes in refractive index and extinction coefficient in the implanted layer as a function of operating wavelength. Here, we report the first observation of decreased refractive index for a wide spectral range in low fluence implanted diamond. In addition, we observe non-monotonic response of the refractive index with fluence, which is in disagreement with proton studies, but accords with other heavy-ion implantation reports. Such discrepancies suggest that there are different mechanisms for refractive index modification for different species and that resulting optical properties are not solely a function of damage. Further comparisons with the white light reflectance and near infra-red transmittance measurements support the SE data.

We present a novel approach to achieving in-plane coupling for ridge waveguides fabricated in single crystal diamond through a modification to the graphitic implant process. The etched cross-section of a diamond ridge structure is examined to confirm roughness estimates and the trenching effect. Finally nanoscale optical cavities are fabricated in polycrystalline diamond using a new method of exposure using focussed ion beam as a hard mask to pattern the structures.

Waveguide structures were fabricated in both nanocrystalline CVD diamond (NCD) and HPHT type 1b single crystal diamond using photolithography and reactive ion etching. The combination of these techniques allows the patterning of many long photonic structures simultaneously, making it easily scalable. Emphasis has been placed on reducing sidewall roughness to prevent loss due to scattering. In single crystal diamond a peak-to-peak roughness of approximately 10 nm (estimated from SEM images) was achieved for the majority of the structure sidewall.

We report on the Raman and photoluminescence characterization of three-dimensional microstructures created in single crystal diamond with a Focused Ion Beam (FIB) assisted lift-off technique. The method is based on MeV ion implantation to create a buried etchable layer, followed by FIB patterning and selective etching. In the applications of such microstructures where the properties of high quality single crystal diamond are most relevant, residual damage after the fabrication process represents a critical technological issue. The results of Raman and photoluminescence characterization indicate that the partial distortion of the sp3-bonded lattice and the formation of isolated point defects are effectively removed after thermal annealing, leaving low amounts of residual damage in the final structures. Three-dimensional microstructures in single-crystal diamond offer a large range of applications, such as quantum optics devices and fully integrated opto mechanical assemblies., 30 pages, 7 figures