Scaling laws of the cavity enhancement for nitrogen-vacancy centers in diamond

TL;DR

This study uses a fiber-based microcavity to explore how cavity parameters influence the enhancement of nitrogen-vacancy center fluorescence, revealing scaling laws and potential for tunable single-photon sources.

Contribution

It explicitly demonstrates the scaling laws of Purcell enhancement by varying mode volume and quality factor in a fiber-based microcavity system.

Findings

Spectral density increased by up to 300 times

Small changes in emission lifetime for broadband emitters

Potential to reach strong-coupling regime

Abstract

We employ a fiber-based optical microcavity with high finesse to study the enhancement of phonon sideband fluorescence of nitrogen-vacancy centers in nanodiamonds. Harnessing the full tunability and open access of the resonator, we explicitly demonstrate the scaling laws of the Purcell enhancement by varying both the mode volume and the quality factor over a large range. While changes in the emission lifetime remain small in the regime of a broadband emitter, we observe an increase of the emission spectral density by up to a factor of 300. This gives a direct measure of the Purcell factor that could be achieved with this resonator and an emitter whose linewidth is narrower than the cavity linewidth. Our results show a method for the realization of wavelength-tunable narrow-band single-photon sources and demonstrate a system that has the potential to reach the strong-coupling regime.