Nontrivial optical response of silicon triangular prisms

The electromagnetic response of silicon triangle nanoprisms in the near-infrared region is investigated. It is revealed that the bianisotropic dipole approximation is insufficient for this geometry since the direct application of the Onsager-Casimir symmetry rule to the dipole response leads to a contradictory conclusion. We show that to resolve this contradiction, it is necessary to take into account the nonlocal contributions of higher orders to the excited electric and magnetic dipole moments of the prisms. However, the inclusion in the consideration of nonlocal corrections to the dipole moments leads to the need to take into account the excitation of multipoles of a higher order than dipoles

Application of Born series for modeling of Mie-resonant nanostructures

Born series formalism is a widely-used approach to solve a scattering problem in quantum mechanics and optics, including a problem of electromagnetic scattering on the ensembles of Mie-resonant nanoparticles. In the latter case, the Born series formalism can be used when the electromagnetic coupling between nanoparticles is weak. This can be violated near the multipole Mie-resonance of the nanoparticle. In this work, we analyze the applicability of the Born series approach for modeling the resonant optical response of Mie-nanoparticle ensembles and formulate quantitative criteria of Born series convergence and, subsequently, the applicability of this approach

Light focusing by silicon nanosphere structures under conditions of magnetic dipole and quadrupole resonances

Metalens is a planar device for light focusing. In this work, we design and optimize c-Si nanosphere metalenses working on the magnetic dipole and quadrupole resonances of the c-Si nanoparticle. Resonant optical response of c-Si nanostructures is simulated by the multipole decomposition method along with the zero-order Born approximation. Limitations of this approach are investigated. The obtained results of optimization are verified by simulation via the T-matrix method

Broadband forward scattering from dielectric cubic nanoantenna in lossless media

Dielectric photonics platform provides unique possibilities to control light scattering via utilizing high-index dielectric nanoantennas with peculiar optical signatures. Despite the intensively growing field of all-dielectric nanophotonics, it is still unclear how surrounding media affect scattering properties of a nanoantenna with complex multipole response. Here, we report on light scattering by a silicon cubic nanoparticle embedded in lossless media, supporting optical resonant response. We show that significant changes in the scattering process are governed by the electro-magnetic multipole resonances, which experience spectral red-shift and broadening over the whole visible and near-infrared spectra as the indices of media increase. Most interestingly, the considered nanoantenna exhibits the broadband forward scattering in the visible and near-infrared spectral ranges due to the Kerker-effect in high-index media. The revealed effect of broadband forward scattering is essential for highly demanding applications in which the influence of the media is crucial such as health-care, e.g., sensing, treatment efficiency monitoring, and diagnostics. In addition, the insights from this study are expected to pave the way toward engineering the nanophotonic systems including but not limited to Huygens-metasurfaces in media within a single framework

Evolution of multipole moments in silicon nanocylinder while varying the refractive index of surrounding medium

Here we use multipole decomposition approach to study optical properties of a silicon nanocylinder in different lossless media. We show that resonant peaks of multipole moments experience red shift, smoothing and broadening. Worth noting that electric multipoles experience bigger red shift than their magnetic counterparts. Our results can be applied to design optical devices within a single framework. © 2020 IOP Publishing Ltd

Magnetic hot-spots in hollow silicon cylinders

Silicon nanoparticles can possess magnetic Mie-resonant response in the visible and near infrared wavelength ranges. In this paper, we consider numerically the features of magnetic hot-spots realized inside silicon nanocylinders at the conditions of the optical magnetic resonances, and show that the intensity of the magnetic field inside nanoparticles with a coaxial through hole can be much stronger than the intensity of incident light waves

Destructive interference between electric and toroidal dipole moments in TiO2 cylinders and frustums with coaxial voids

We demonstrate numerically the possibility of multipole interference in the TiO2 (titanium dioxide) microcylinders and microfrustums in the wavelength range 210-300 μm. Resonantly strong destructive interference between toroidal and electric dipole contributions to the scattered field is achieved by a geometry tuning. The toroidal and electric dipole mode overlapping at the resonant wavelength with almost total suppression of the total electric dipole moment is achieved