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  1. Abstract We have studied optical properties of single-layer and multi-fold nanoporous gold leaf (NPGL) metamaterials and observed highly unusual transmission spectra composed of two well-resolved peaks. We explain this phenomenon in terms of a surface plasmon absorption band positioned on the top of a broader transmission band, the latter being characteristic of both homogeneous “solid” and inhomogeneous “diluted” Au films. The transmission spectra of NPGL metamaterials were shown to be controlled by external dielectric environments, e.g. water and applied voltage in an electrochemical cell. This paves the road to numerous functionalities of the studied tunable and active metamaterials, including controlmore »of spontaneous emission, energy transfer and many others.« less
    Free, publicly-accessible full text available December 1, 2022
  2. Abstract We have grown arrays of silver nanowires in pores of anodic alumina membranes (metamaterials with hyperbolic dispersion at λ  ≥ 615 nm), spin coated them with the dye-doped polymer (HITC:PMMA), and studied the rates of radiative and nonradiative relaxation as well as the concentration quenching (Förster energy transfer to acceptors). The results were compared to those obtained on top of planar Ag films and glass (control samples). The strong spatial inhomogeneity of emission kinetics recorded in different spots across the sample and strong inhibition of the concentration quenching in arrays of Ag nanowires are among the most significant findings of thismore »study.« less
    Free, publicly-accessible full text available October 4, 2022
  3. Abstract We have studied the dependence of concentration quenching of luminescence (donor–acceptor energy transfer) on the thickness d of dye-doped polymeric films (HITC:PMMA) and found its strong inhibition at small values of d . This phenomenon is tentatively explained by a limited number of acceptors, which donors’ excitation can reach in thin samples, if the film’s thickness is comparable to the diffusion length of the energy transfer. The latter mechanism, along with effective reduction of the dye concentration, is responsible for an inhibition of the concentration quenching of dye molecules impregnating porous alumina membranes. The elongation of emission kinetics inmore »thick (≥3 μm) HITC:PMMA films is cautiously attributed to the samples’ crystallinity.« less
    Free, publicly-accessible full text available August 19, 2022
  4. Abstract We present a microscopic model describing the transition to a strong coupling regime for an emitter resonantly coupled to a surface plasmon in a metal–dielectric structure. We demonstrate that the shape of scattering spectra is determined by an interplay of two distinct mechanisms. First is the near-field coupling between the emitter and the plasmon mode which underpins energy exchange between the system components and gives rise to exciton-induced transparency minimum in scattering spectra prior to the transition to a strong coupling regime. The second mechanism is the Fano interference between the plasmon dipole and the plasmon-induced emitter’s dipole asmore »the system interacts with the radiation field. We show that the Fano interference can strongly affect the overall shape of scattering spectra, leading to the inversion of spectral asymmetry that was recently reported in the experiment.« less
    Free, publicly-accessible full text available August 19, 2022
  5. We demonstrated amplified spontaneous emission (ASE) enabled by evanescent gain at an interface between two adjacent dielectrics. The ASE wave is outcoupled to the high-index medium at the critical angle, enabling observation of spectacular emission rings.
  6. We have studied the dependence of concentration quenching of luminescence on the thickness d of dye-doped polymeric films (HITC:PMMA) and found a strong inhibition of the donor-acceptor energy transfer (concentration quenching) at small values of d.