Characteristics of electric quadrupole and magnetic quadrupole coupling in a symmetric silicon structure

Abstract

Multipole interferences have attracted a lot of interests in last decade due to extraordinary performance on beam control and scattering shaping. However, most of previous works focused on the dipole-based interferences while the quadrupole modes and other high-order multipole modes with unique properties were of less attention. In this work, we aim to expand the present dipole-based multipole-interference regime to the quadrupole-interference regime. We study the interference between an electric quadrupole (EQ) and a magnetic quadrupole (MQ) in both isolated and periodically arranged homogeneous cross dielectric structure. Through structural parametric control, the EQ and MQ can be precisely tuned to share the same resonant intensity at a specific wavelength, resulting in a generalized Kerker effect. Moreover, a dark MQ mode, which is orthogonal with the original MQ mode, arises when we increase the interaction between structure. We find that the spectral approaching between dark MQ and original bright EQ results in an EIT effect and Fanoshaped spectral reflection response. The induced Fano spectrum possesses tunable quality factors varying from ∼10 to >10 5 with the variation of EQ-MQ coupling efficiency. The numerically derived maximum quality factor (238, 618) of the dielectric EQ-MQ coupling system even exceeds the quality factors of many plasmonic resonant systems. We also prove that such spectrum can be adopted to refractive index sensing. Besides, we show that EQ-MQ coupling can bring about rapid 2π phase change, which can be applied in metasurface designs. These results and conclusions about the EQ-MQ interference systems can provide a promising avenue for advanced optical devices.

Tuning dipolar and multipolar resonances of chiral silicon nanostructures for control of near field superchirality

“…16 Multipolar resonances are more complex and are described elsewhere. 17 The reflectance response of the RS metasurfaces are qualitatively like that of the other three. There is a very strong similarity between y-polarised RS spectra for 160 to 210 nm thick substrates and those from the other arrays.…”

“…The more dominant M Q contributions for the thicker sample can be rationalised by considering that the magnetic components of the resonances are parallel to the incident light excitation, therefore, as the silicon depth is increased, M Q is better supported across the height of the structures. 17…”

Low-Variance Surface-Enhanced Raman Spectroscopy Using Confined Gold Nanoparticles over Silicon Nanocones

“…Their presence creates destructive interference in the far-field , due to resonance frequency matching of electric and magnetic Mie type multipoles. Usually, this is achieved by tuning the dimensions in symmetric and asymmetric structures …”

“…Usually, this is achieved by tuning the dimensions in symmetric and asymmetric structures. 49 Different from the anapole state, the observed modal distribution can also be described by the Mie scattering theory. Murphy and Brueck showed that the magnetic dipole resonance wavelength is proportional to the product of the refractive index, n, of the particle and its diameter D so that λ MD = nD.…”

Special scattering regimes for conical all-dielectric nanoparticles

“…ED + MD Silicon spherical nanoparticles 55,63 -ED + EQ Plasmonic gold nanoring nanoantenna 25 -ED + MQ -Ceramic spheroidal particle 64 Silicon square nanoplate 62 MD + EQ -Core-shell SiO2@InSb and Si@InSb in a one-dimensional (1D) metalattice geometry in the Terahertz range 65 MD + MQ Ceramic core-shell 66 -EQ + MQ Both isolated and periodically arranged homogeneous cross dielectric structure 67 -ED + MD + EQ + MQ Individual core-shell nanoparticles 68 Silicon cube 29 Ceramic cube and cylinder 30 Vol:. ( 1234567890) www.nature.com/scientificreports/ than the EQ and MD.…”