Shaping the Fluorescent Emission by Lattice Resonances in Plasmonic Crystals of Nanoantennas

Abstract

We demonstrate that the emission of light by fluorescent molecules in the proximity of periodic arrays of nanoantennas or plasmonic crystals can be strongly modified when the arrays are covered by a dielectric film. The coupling between localized surface plasmon resonances and photonic states leads to surface modes which increase the density of optical states and improve light extraction.Excited dye molecules preferentially decay radiatively into these modes, exhibiting an enhanced and directional emission.

Surface modes in plasmonic crystals induced by diffractive coupling of nanoantennas

“…In this case, diffractive coupling due to the scattering of light by the array produces narrow extinction resonances, which have been demonstrated experimentally very recently. [12][13][14][15] Such resonances exhibited by arrays of nanoantennas are a signature of the excitation of lattice surface modes extending in the plane of the array. This Rapid Communication investigates the characteristic lengths of lattice surface modes on plasmonic crystals of nanoantennas.…”

“…1͑a͒ around 650 nm corresponds to the excitation of the half-wave localized plasmon resonance of the individual nanoantennas. 15 Figure 2͑a͒ displays the zero-order transmittance spectra measured as a function of the angle of incidence in the range of 6 -60°. These measurements are presented as a function of the reduced frequency / c and k ʈ , where k ʈ = k ʈ x = k 0 sin͑ ͒x is the real part of the wave vector component in the plane of the array along the x direction and k 0 = / c. In the range of angles of the measurements of Fig.…”

“…The LSPR is related to the flat dispersion ͑black squares͒ around 0.0095 rad nm −1 . 15 The dispersion curves of the surface modes are at lower frequencies than the adjacent photon dispersion lines, which represent the Rayleigh anomaly conditions related to the ͑1,0͒ and ͑−1,0͒ diffractive orders ͑solid and dashed lines in Fig. 3͑a͒, respectively͒.…”

“…An efficient diffractive coupling between nanoantennas is obtained when the array is embedded in a homogeneous dielectric environment. [13][14][15] Therefore, we put an amorphous quartz upperstrate on top of the antenna array. Good optical contact between substrate and upperstrate was obtained with a thin layer of refractive index matching liquid.…”

Diffractive arrays of gold nanoparticles near an interface: Critical role of the substrate

“…[1][2][3] The subject has recently received renewed attention 4,5 with the prediction 6,7 and experimental observation [8][9][10][11][12] of interesting optical phenomena that result from the interaction between the geometrical resonance associated with light diffraction and the excitation of localized surface-plasmon resonances in metallic nanoparticles, which play the role of plasmonic nanoantennas. 13 In addition to the interesting physics revealed in such systems, a number of applications have been proposed, including nanoscale energy transport, 14,15 sensing, 16,17 and modifying spontaneous emission, 18 which rely on the improved quality factor resulting from the reduction in radiative damping of the array as compared to localized plasmons excited in isolated particles. Recent advances in the control of the angular emission from quantum dots are also based on diffractive coupling of antenna elements.…”