Role of emitter position and orientation on silicon nanoparticle-enhanced fluorescence

Abstract

High-index spherical dielectric nanoparticles are explored as templates for tailoring the fluorescence of nearby electric point-dipole-like emitters. The role of emitter orientation and position around the nanosphere on the modification of both its excitation and its emission rate is studied rigorously through derivation of appropriate analytic solutions. It is shown that dielectric nanoparticles, which support a richness of optical modes of electric or magnetic character and thus a variety of mechanisms for near-field enhancement, provide moderate fluorescence enhancement factors—as compared, e.g., to their plasmonic counterparts—which survive, however, for a wide range of emitter positions and orientations. Understanding the physical mechanisms governing this behaviour, which offers a promising route towards efficient control of the emission properties of randomly arranged emitters, is widely facilitated by the existence of analytic expressions such as the ones derived here. Further enhancement can be achieved by designing nanoparticle-aggregate antennas, or by combining dielectric and plasmonic components.

Disentangling cathodoluminescence spectra in nanophotonics: particle eigenmodes vs transition radiation

“…The spectra of Mie-resonant NPs are characterised by multipoles of both electric and magnetic character, 30 Fano resonances, 31 anapoles, 32 and bound states in the continuum, 33 and have enabled functionalities as diverse as directional light scattering 34,35 and emission, 36 directional couplers, 37,38 and Huygens-based metasurfaces. 39,40 All-dielectric nanodevices are thus proposed as promising alternatives to plasmonics, with possible applications in biosensing, 41,42 nanoantennas, 43,44 slow light, 45 thermo-optic tuning, 46 ultraviolet interband plasmonics, 47 fluorescence control, [48][49][50] and Mie-exciton strong-coupling phenomena. [51][52][53][54] CL measurements are performed with the set-up shown schematically in the left-hand sketch of Figure 1a (see Methods for details).…”

“…The colour map of Figure 1b shows experimental CL spectra for a relatively small NP (R = 62 nm) -for which modal characters should be straightforward to assign-as a function of impact parameter. With vertical dashed lines we show the energies where different mul- tipoles are predicted by Mie theory 49 for this NP size (for extinction spectra and their multipolar decomposition, see Supporting Information). Two resonances manifest clearly in the spectra for large impact parameters: a sharp magnetic dipole (MD) at about hω = 2.35 eV, and a broader and less intense electric dipole (ED) around 2.75 eV.…”

Probing the Optical Response and Local Dielectric Function of an Unconventional Si@MoS2 Core–Shell Architecture

“…One outstanding feature of TMDs is their large exciton binding energy and exciton transition dipole moment, making them strong candidates as quantum emitters for next-generation photonics even at room temperature . Reports have been made on improving the functionality of the TMDs by encapsulating a nanosphere core material, such as Au, , Ag, , and Si. , In such core–shell architectures, light–matter interactions are enhanced by the surface interaction between the core and the shell . This is promising for optoelectronic applications such as exciton–polariton lasers, light-emitting devices, and all-optical switches .…”

Disentangling Cathodoluminescence Spectra in Nanophotonics: Particle Eigenmodes vs Transition Radiation

“…In what follows, we choose to analyze the emission properties of Si NPs because of their high refractive index and low ohmic losses, the multitude of coexisting modes in the visible , (with the field largely confined inside the NP, thus calling for traversing electron beams), and the relatively large sizes required for the full glory of all Mie resonances to unveil itself; the combination of these features can significantly pronounce the interference effects under study. The spectra of Mie-resonant NPs are characterized by multipoles of both electric and magnetic character, Fano resonances, anapoles, and bound states in the continuum and have enabled functionalities as diverse as directional light scattering , and emission, directional couplers, , and Huygens-based metasurfaces. , All-dielectric nanodevices are thus proposed as promising alternatives to plasmonics, with possible applications in biosensing, , nanoantennas, , slow light, thermo-optic tuning, ultraviolet interband plasmonics, fluorescence control, − and Mie-exciton strong-coupling. − …”

“…The color map of Figure 1b shows experimental CL spectra for a relatively small NP (R = 62 nm) (for which modal characters should be straightforward to assign) as a function of impact parameter. Vertical dashed lines indicate the energies where different multipoles are predicted by standard Mie theory 55 for this NP size (for extinction spectra and their multipolar decomposition, see Supporting Information). Two resonances manifest clearly in the spectra for large impact parameters: a sharp magnetic dipole (MD) at about ℏω = 2.35 eV and a broader and less intense electric dipole (ED) around 2.75 eV.…”