Carbon nanotubes can emit single photons in the visible range as well as in the telecom band, depending on their diameter, making them promising candidates for quantum cryptography. We have built a very high finesse tunable microcavity in order to study quantum optics and increase the emission efficiency of such emitters. Our original geometry, consists in studying thoroughly the photoluminescence of a single carbon nanotube deposited on a Bragg mirror with a classical confocal microscope and then enclose it into a cavity by approaching a concave mirror machined by CO2 laser ablation at the apex of an optical fiber.
The emission is enhanced by a Purcell factor of up to 6 while retaining the narrow linewidth given by the cavity finesse (<80 GHz) and the tunability given by the emitter’s linewidth (5 THz). Given the strong sub-poissonian statistics of the emission in cavity, this study paves the way to carbon-based on-demand tunable single-photon sources in the telecom bands.