Förster Resonance Energy Transfer inside Hyperbolic Metamaterials

Abstract

The ability to control Förster Resonance Energy Transfer (FRET) between emitters via the design of nanostructured materials with appropriate electromagnetic properties is important in the development of fast and enhanced sources of illumination, high-efficiency photovoltaic devices and biomedical applications, such as nanorulers. While the engineering of the local density of states allows an efficient control over the spontaneous emission rate, its influence on the FRET process has been an ongoing debate and has led to disparate experimental and theoretical results. In particular, hyperbolic metamaterials have recently been shown to drastically increase the fluorescence decay rate. Here, we experimentally demonstrate an increase in the FRET rate for Donor-Acceptor (D-A) pairs separated by fixed distances (3.4, 6.8 and 10.2 nm) located inside a hyperbolic metamaterial comprised of an array of gold nanorods. While the modification of the local density of states surrounding the D-A pairs strongly influences the FRET rate, leading to a 13-fold increase inside the metamaterial, the FRET efficiency is shown to remain mostly unaffected. For comparison, we also study the modification of energy transfer rate and efficiencies of D-A pairs placed on top of a gold film, on top of a nanorod-based metamaterial and inside a nanorod-based metamaterial coated with polymer in order to prevent quenching. The free-space emission intensities of the acceptor were also investigated, leading up to an 18-fold increase in the emission intensity. The designed

Site-selective functionalization of plasmonic nanopores for enhanced fluorescence emission rate and Förster resonance energy transfer

“…Then, in Figure 5(b) we see that the FRET efficiency is almost constant for large nanopore sizes (30% and 31%), and then it increases as the size of the nanopore shrinks. Despite the fact that the distance between the dyes is not constant, the efficiency values obtained are comparable to those obtained by some other groups using similar structures 22 . The efficiency vs size behaviour is also quite intuitive: we assume that the dyes are attached onto the wall of the nanopore at a constant rate.…”

Extending Single-Molecule Förster Resonance Energy Transfer (FRET) Range beyond 10 Nanometers in Zero-Mode Waveguides

“…Several contributions have explored the influence of nanophotonics for FRET using microcavities, 18,[22][23][24] mirrors, [25][26][27][28][29] nanoparticles, [30][31][32][33][34][35][36][37] nanoapertures, [38][39][40][41][42][43][44] nanoantennas, [45][46][47][48][49] waveguides, 50 or hyperbolic metamaterials. 51,52 However, none of these works has clearly demonstrated experimentally the enhancement of the smFRET detection range in the near field. Actually, most cases consider short donor-acceptor separations (on the order or below the Förster radius) in order to ease the optical detection.…”

“…Actually, most cases consider short donor-acceptor separations (on the order or below the Förster radius) in order to ease the optical detection. 23,25,36,37,46,47,52 It should be acknowledged that long range energy transfer over distances up to several micrometers has been reported, [53][54][55][56][57][58] but these studies are based on radiative dipole-dipole coupling (i.e. energy transfer mediated by a propagating photon or plasmon in the far field).…”

Singlet–Triplet Transition Rate Enhancement inside Hyperbolic Metamaterials

“…Most of the experimental studies involving hyperbolic metamaterials reported Purcell factors of several tens, reaching ≈80 with additional structuring of a metal‐dielectric multilayer metamaterial . In nanorod‐based hyperbolic metamaterials, decay rate enhancements of dipolar emitters reaching up to 100 were observed, depending on the positioning of the emitters in the unit cell as well as the material losses, and led to emission in both free space and waveguided modes of the metamaterial slab …”

“…[16] In nanorod-based hyperbolic metamaterials, decay rate enhancements of dipolar emitters reaching up to 100 were observed, depending on the positioning of the emitters in the unit cell as well as the material losses, [9] and led to emission in both free space and waveguided modes of the metamaterial slab. [15,17] Spontaneous emission from other atomic transitions has, however, not been extensively investigated, mostly due to their conventionally forbidden character strictly controlled by selection rules. Electric-dipole-forbidden atomic transitions, such as magnetic-dipole transitions, multipolar transitions with orbital angular momentum changes, spin-flip-required, or singlettriplet transitions, are typically orders of magnitude slower than regular dipolar transitions between selection-rule-allowed states, and therefore are hardly experimentally observable.…”