The dual-frequency zero-backward scattering realized in a hybrid metallo-dielectric nanoantenna

Abstract

In this paper, we propose a hybrid metallo-dielectric core-shell nanorod for the Kerker-type effect at two different frequencies. The effect arises from the interference of the scattering waves of the nanorod, which are generated by the magnetic dipole moment (MD) of the high-index hollow particle and the electric dipole moment (ED) induced in both metallic and dielectric particles. Interestingly, we find that such kind of unidirectional radiation properties, (i.e., zero back scattering occurring at dual frequencies) can be sustained with a single nanorod, which usually being equivalent to a local electric dipole source. The effect of substrate is also considered to investigate the typical experimental realization for the dual-frequency unidirectionalities of the nanoantenna. Furthermore, the unidirectionality can be further improved by the design of one-dimensional array of the hybrid nanoantenna. Our results could provide an additional degree of freedom for light scattering manipulation, and widen the versatile applications in nanoantennas, optical sensor, light emitters, as well as photovoltaic devices.

Subwavelength Silicon Nanoblocks for Directional Emission Manipulation

“…The scattered electric far field resulting from the combination of these induced multipoles can be calculated by [ 13 , 27 ] in which P ( M ) is the electric (magnetic) dipole moment, Q E is the electric quadrupole tensor.…”

“…Studies have shown the unique capability to create unidirectional light radiation in multiple architectures, including single-element nanospheres [ 8 , 9 ], nanodisks [ 11 , 12 , 13 , 14 , 15 ], nanowires (cylinders) [ 16 , 17 , 18 , 19 ], rectangular patches [ 20 ], V-shaped [ 21 ] and stair-shaped nanoantennas [ 22 ], as well as multi-element array nanoantennas [ 23 , 24 , 25 , 26 ]. There are also many efforts in the field to achieve bi- or multi-directional scattering/emission [ 9 , 13 , 15 , 21 , 23 , 27 , 28 ]. In such a context, all-dielectric antennas are typically designed with broad Mie resonances, which allow for spectral overlaps between different multipolar modes at multi-wavelength positions.…”

Tunable Unidirectivity of Metal-Dielectric-Metal Plasmonic Nanoantennas With PT-Symmetric Potentials

“…, c is the speed of light in vacuum, ε d is the relative permittivity of dielectric surrounding, r = |r| and n = r/r is the unit vector in the direction of observation, p (m) is the electric (magnetic) dipole moment, Q e (Q m ) is the electric (magnetic) quadrupole tensor, and T is the tensor of the toroidal dipole moment [59]. The multipole decompositions are accomplished in both the Cartesian basis (source-representation) and the spherical basis (field-representation).…”

“…is the permittivity of free space, ε r is the relative permittivity of particle, E ω (r) is electric field distribution. Multipole contributions show that the resonance peaks correspond to the overlap of several different multipole decomposition of the scattered field [59]. The scattering cross sections C sca are defined from farfield scattered power (I) by normalizing to the energy flux of the incident wave (I inc ).…”

“…Here, ω is the angular frequency, c is the speed of light in a vacuum, the more high-order multipoles are not shown [59]. Figure 1A shows schematic of the multi-layered metaldielectric-metal (MDM) nanoantenna.…”