Individual color centers in diamond are bright, photo-stable emitters of fluorescence. Whereas e.g. nitrogen vacancy (NV) centers additionally offer electronic spins that can be coherently manipulated and read-out conveniently at room temperature, silicon vacancy (SiV) centers offer especially narrow emission (zero-phonon-line, ZPL) at room temperature. Color centers in diamond are versatile sensors, e.g. NV spins are highly-sensitive to electric and magnetic fields , while SiV centers have been recently used as optical temperature sensors . The high stability of color centers also makes them promising candidates for novel scanning near field microscopy techniques . To fully harness the potential of atomic-sized color centers as sensors, it is mandatory to create individual color centers close to the diamond surface and to bring them near (< 100 nm) the sample under investigation. Simultaneously, all techniques mentioned above are using the fluorescence of the color centers to read out the sensor. Thus, the approach of choice to obtain truly nanoscale resolution, not limited by optical resolution, is to incorporate single color centers into nanophotonic structures to enhance fluorescence collection and use them in a scanning probe geometry [4,5].
The talk discusses tip-like nanophotonic structures for scanning probe sensing. I will cover the optimization of these structures via simulations as well as different strategies for their fabrication (bottom up and top down, ). Due to the proximity of the color centers to the surface (typically < 10 nm), it is highly crucial to chemically control the termination of the surface to stabilize the charge state and to avoid any damage during nanofabrication processes. We will discuss our results on these topics considering color centers in nanostructures.
Finally, we will summarize our steps towards novel sensing approaches with color centers, including experiments to establish near field based energy transfer (FRET) with color centers inside a diamond single crystal.
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