Cavity-enhanced Raman scattering for <i>in situ</i> characterization of solid-state microcavities

The nitrogen vacancy centre (NV) in diamond constitutes a promising node in a quantum network owing to its highly coherent, optically addressable electron spin. However, scalability to more than a few network nodes is limited by the modest entanglement rates. One key issue is the poor extraction efficiency of coherent photons out of the host material. This issue can be addressed by coupling single NV centres to a resonant cavity, greatly enhance the photon flux owing to the Purcell effect [1].

Contrary to monolithic resonators, open Fabry-Perot cavities require in situ mode-matching of the cavity mode to external optics. This is a laborious and non-trivial task if a single emitter is used, as appreciable count rates can only be achieved for close-to-optimal coupling. To this end, we show that the Raman scattering from the solid-state host can be harnessed for in situ characterisation and optimisation of the cavity mode [2]. We demonstrate a 58.8-fold enhancement of the Raman transition compared to confocal measurements under similar conditions. Furthermore, replacing the detection optics with a CCD camera enables single-shot images of the modes’ lateral profile.

1 Phys. Rev. X 7, 031040 (2017)
2 Phys. Rev. Appl. 13, 014036 (2020)