"Cavity-enhanced single photon sources and scanning cavity microscopy with fiber-based optical microcavities"

"Microscopic Fabry-Perot cavities built from laser-machined optical fibers offer small mode volumes and large quality factors combined with full tunability and direct access to the cavity field.In my talk I will present experiments where we harness these properties for enhanced light - matter interaction with solid-state based quantum- and nanosystems. Fiber cavities promise a route for efficient and narrow-band single-photon sources by means of Purcell enhancement of fluorescence emission. We couple colour centers in diamond nanocrystals such as the NV center to a cavity and study the scaling laws of the cavity enhancement for a large range of parameters. I will discuss our current efforts to achieve broadband enhancement with ultra-small mode volume cavities and to generate indistinguishable single photons under ambient conditions. In the context of microscopy, multiple interaction of probe light with a sample placed inside a microcavity promises an increase in sensitivity on the order of the cavity Finesse, which can reach values >10^5 for fiber cavities. We demonstrate a scheme for scanning cavity microscopy, which provides spatially and spectrally resolved maps of various optical properties of a sample with superior sensitivity. The method should enable studies of individual non-flourescent macromolecules and weakly absorbing nanoparticles."