All-Dielectric Silicon Nanogap Antennas To Enhance the Fluorescence of Single Molecules

Abstract

Plasmonic antennas have a profound impact on nanophotonics as they provide efficient means to manipulate light and enhance light-matter interactions at the nanoscale. However, the large absorption losses found in metals can severely limit the plasmonic applications in the visible spectral range. Here, we demonstrate the effectiveness of an alternative approach using all-dielectric nanoantennas based on silicon dimers to enhance the fluorescence detection of single molecules. The silicon antenna design is optimized to confine the near-field intensity in the 20 nm nanogap and reach a 270-fold fluorescence enhancement in a nanoscale volume of λ(3)/1800 with dielectric materials only. Our conclusions are assessed by combining polarization resolved optical spectroscopy of individual antennas, scanning electron microscopy, numerical simulations, fluorescence lifetime measurements, fluorescence burst analysis, and fluorescence correlation spectroscopy. This work demonstrates that all-silicon nanoantennas are a valid alternative to plasmonic devices for enhanced single molecule fluorescence sensing, with the additional key advantages of reduced nonradiative quenching, negligible heat generation, cost-efficiency, and complementary metal-oxide-semiconductor (CMOS) compatibility.

Electromagnetic polarization-controlled perfect switching effect with high-refractive-index dimers and the beam-splitter configuration

“…However, the challenge of building good sphere dimmers with controlled separation still remains although there are some recent good examples in the literature, like those in refs 23, 40. Other geometries like either cubes41 or cylinders1142 could constitute suitable alternatives for building this kind of dimer units. Also, with reference to the experiment in the optical range, the widely used backward dark field microscope configuration (BDFMC) (see for instance, refs 17, 43 among others) could be used to reproduce the results contained in this research, although our findings are mainly addressed to a final in-plane optical-board set-up.…”

Modifying magnetic dipole spontaneous emission with nanophotonic structures

“…Shortly after, the concept of ” magnetic light ” has been experimentally observed in the visible , infrared , and microwave frequency ranges. Such nanoparticles have attracted significant attention for their resonant behavior and thus have been widely employed for enhancing the light‐matter interaction .…”

All-Optical Switching and Unidirectional Plasmon Launching with Nonlinear Dielectric Nanoantennas

“…In the last several years high-index dielectric nanoparticles and nanostructures [1][2][3] proved to be a promising platform for various nanophotonic applications, in particular for the design of functional nanoantennas [4][5][6], enhanced spontaneous emission [7][8][9][10], photovoltaics [11], frequency conversion [12][13][14], Raman scattering [15], and sensing [16]. The great interest in such nanostructures is caused mainly by their ability to control the electric and magnetic components of light at the nanoscale [1], while exhibiting low dissipative losses inherent to the materials with a negligible concentration of free charges [16].…”