Plasmonic Moon: A Fano-Like Approach for Squeezing the Magnetic Field in the Infrared

Abstract

Outstanding results have been achieved in the localization of optical electric fields via ultrasmall plasmonic cavities, paving the way to the subdiffractive confinement of local electromagnetic fields. However, due to the intrinsic constraints related to conventional architectures, no comparable squeezing factors have been managed yet for the magnetic counterpart of radiation, practically hindering the detection and manipulation of magneto-optical effects at the nanoscale. Here, we observe a strong magnetic field nanofocusing in the infrared, promoted by the induction of a coil-type Fano resonance. By triggering the coil current via a quadrupole-like plasmonic mode, we straightforwardly boost the enhancement of the infrared magnetic field and perform its efficient squeezing in localized nanovolumes.

Plasmonic Sensing and Modulation Based on Fano Resonances

“…At appropriate structural parameters, the Fano resonance can evolve into the classical analogue of electromagnetically induced transparency (EIT; usually termed as plasmon induced transparency, PIT), where the narrow subradiant resonances are exactly located on the center of the radiant resonances . The typical arranged metallic nanostructures include the nonconcentric ring/disk, clusters of plasmonic nanoparticles, symmetry‐breaking dolmen‐style nanoslabs, and nanoring/disk dimers . For example, in the nonconcentric arrangement of a disk and a ring (Figure e), both the narrow subradiant and broad radiant plasmon modes were supported .…”

Coupling phenomena and collective effects in resonant meta-atoms supporting both plasmonic and (opto-)magnetic functionalities: an overview on properties and applications [Invited]

“…Adapted from ref. [190]. (e) A sketch of the simulated system with the nomenclature used in the text.…”

“…Shafiei et al [189] demonstrated that a subwavelength plasmonic metamolecule consisting of four closely spaced gold nanoparticles supports strong magnetic response. Toma et al demonstrated that coil-like dark modes and high-order plasmonic modes hybridization can generate strong magnetic effects in the mid-IR by using either planar asymmetric-disks or moon-integrated trimers [190,191] (see also Fig. 5).…”

Three-dimensional concentration of light in deeply sub-wavelength, laterally tapered gap-plasmon nanocavities

“…Given the magnetic nature of the fundamental resonance mode of the MIM periodic pattern, similarly to other works in the literature, 23 we quantified the achieved confinement by calculating an effective mode volume defined as: H field and along the y-and z-axes by the positions at which the H-field decays to 1/e of its maximum value at the metaldielectric interface (see Figure 3(c)). The inset of Figure 4 shows the change in the mode extension along the x-, y-, and z-directions as a function of the W neck .…”