Figure I: Schematic of the considered configuration. A single nanodiamond hosting a single nitrogen vacancy centre (NV) is placed inside a V-groove channel waveguide. On excitation with a laser, the NV center couples, in ideal case, all of its emission into the VG-supported CPP mode. The channeled emission out-couples from the VG via the tapered nanomirrors at the VG extremities.

Figure II: Scanning electron microscopy (SEM) image of a 10-mm- long V-shaped groove (B315-nm-width and B510-nm-depth) fabricated by milling a thick gold film with a FIB. The scale bar is 1 mm.

Figure III: Total electric field profile of the VG-supported CPP mode for a wavelength of 650 nm as calculated with COMSOL software.

Coupling of individual quantum emitters to channel plasmons

Bermudez-Ureña E., Gonzalez-Ballestero C., Geiselmann M., Marty R., Radko I. P., Holmgaard T., Alaverdyan Y., Moreno E., Garcia-Vidal F. J., Bozhevolnyi S. I:, & Quidant R., Nature Commun. 6, 7883 (2015)

Motivation of the modeling

One of the main challenges in developing future nanoscale quantum photonic circuits is to manage combining on a single chip a single photon source, waveguides,
modulators and detectors. An important milestone towards this ultimate goal is the deterministic coupling of a single quantum emitter to an integrated waveguide.

Achievements of the model

We first used numerical simulations to model the coupling between a quantum emitter and the V-groove plasmonic channel. Once an optimal theoretical configuration was identified, the experimental team used state-of-the-art techniques to assemble the structure using a single nitrogen vacancy centre, a single quantum emitter present in diamond, coupled to the channel plasmons supported by a V-groove channel. The observations obtained from the experiment revealed
efficient coupling of the NV centre emission to the propagating modes of the V-groove, in accordance with the theoretical predictions postulated by the theoretical team.

Model system/Software

Electromagnetic calculations were performed using a Finite Element Method as implemented in the COMSOL multiphysics tool.

The following key information was provided by the numerical simulations:

  • Optimum geometry for the V-groove (aperture angle and depth) for carrying channel plasmons at the emission frequency of the quantum emitter, i.e., nitrogen vacancy.
  • Optimum location of the nitrogen vacancy inside the V-groove for which the coupling with the channel plasmon supported the V-groove is maximum.

Francisco J. García Vidal, part of the SIMUNE´s board of experts is one of the authors of this work.