Institut des
NanoSciences de Paris
insp
insp
1.jpg

Deterministic coupling to a nano-antenna

An antenna is a device which enhances the coupling between a local electric oscillator and the propagating waves of the electromagnetic waves. Antennas are widely used for the emission and reception of radio waves, but their visible counterparts have only been considered recently as their dimensions must be controlled with wavelength-scale precision. Positioning the light emitter with respect to the antenna is an especially delicate aspect of coupling.

We have fabricated patch nano-antenna where the emitter is located 15 nm above a metallic plane and 15 nm below a metallic disk of 1 to 2 µm (fig. 1a). The emitter was a bright agregate of 50-100 nanocrystals (collab. ESPCI). The centering of the metallic disk on the agregate was obtained by a fabrication protocol by « in-situ lithography » performed by P. Senellart at the LPN (our group is presently working at the INSP on adapting this protocol to single nanocrystals).

The imaging of the antenna by fluorescence microscopy shows that the emission originates from the whole antenna surface (so it indeed originates from the plasmonic modes of the antenna) and that the emission intensity is about 10 times the intensity of the neighbouring emitters not coupled to an antenna (fig. 1b). The emission decay is between 4 and 14 times faster than in the reference homogeneous medium (fig. 1c). A more sophisticated analysis of the decays can distinguish between the acceleration of the horizontal and vertical dipole components (fig. 1d) and shows an acceleration of the decay by factors 20 to 80 for a vertical dipole and 1 to 4 for a horizontal dipole.

Figure 1 : (a) Schematic of the patch antenna ; (b) observation by fluorescence microscopy (collab. IOGS) : the emitter at the center is coupled to an antenna and appears much brighter than the neighbouring non-coupled emitters ; (c) decay curves of three different antennas with different diameters (red) and an emitter in a reference medium (homog. silica) ; (d) acceleration factors extracted for a vertical dipole (blue) and a horizontal dipole (red).

 

Collaborations :
- Pascale Senellart at the LPN (Marcoussis)

- Jean-Jacques Greffet and François Marquier at the IOGS (Palaiseau)

- Benoît Dubertret and Thomas Pons at the ESPCI (Paris)

 

Communications :

- C. Belacel, A. Raj Dhawan, F. Bigourdan, B. Habert, X. Lafosse, F. Marquier, L. Coolen, B. Dubertret, J.-J. Greffet, P. Senellart et A. Maître, Deterministical coupling of nanocrystal to plasmonic patch antenna : Purcell effect and directionality, International Conference on Nanoscience + Technology (ICN+T), Vail (Etats-Unis), 21-25 juillet 2014,

- C. Belacel, A. Raj Dhawan, B. Habert, F. Bigourdan, F. Marquier, L. Coolen, X. Lafosse, B. Dubertret, J.-J. Greffet, P. Senellart et A. Maître, Purcell effect and directional emission in a plasmonic patch antenna, Spie Photonics Europe (Bruxelles, 14-18 avril 2014)

- C.Belacel, B.Habert, F. Bigourdan, C. Javeaux, L. Coolen, C.Schwob, S.Michaelis De Vasconcellos, X.Lafosse, B. Dubertret, F. Marquier, P. Senellart, JJ. Greffet, A. Maître, Emission in plasmonics patch nanoantennas, Surface Plasmon Polariton 6, Ottawa (27-31 mai 2013),

- C.Belacel, B.Habert, F. Bigourdan, C. Javeaux, L. Coolen, C.Schwob, S.Michaelis De Vasconcellos, X.Lafosse, B. Dubertret, F. Marquier, P. Senellart, J.-J. Greffet et A. Maître, Emission in plasmonics patch nanoantennas, Photonics West, San Francisco 02/2013

- C. Belacel, B. Habert, F. Bigourdan, F. Marquier, J.-P. Hugonin, S. Michaelis de Vasconcellos, X. Lafosse, L. Coolen, C. Schwob, C. Javaux, B. Dubertret, J.-J. Greffet, P. Senellart et A. Maître, Controlling Spontaneous Emission with Plasmonic Optical Patch Antennas, Nano Lett. 13, 1516 (2013),

- C. Belacel, X. Lafosse , B. Malher, B. Dubertet, A. Maître , P. Senellart, Nanocristaux en cavité micropilier en vue de la réalisation d’une source de photons uniques efficace à température ambiante, Journées Nationales de l’Optique Guidée, Besançon, 20-22 octobre 2010,