Abstract
High refractive index dielectric nanoparticles show high promise as a complementary nanophotonics platform due to compared with plasmonic nanostructures low absorption losses and the co-existence of magnetic and electric resonances. Here we explore their use as resonantly enhanced directional scatterers. We theoretically demonstrate that an asymmetric dimer of silicon nanoparticles shows tuneable directional scattering depending on the frequency of excitation. This is due to the interference between electric and magnetic dipoles excited in each nanoparticle, enabling directional control of the scattered light. Interestingly, this control can be achieved regardless of the polarization direction with respect to the dimer axis; however, difference in the polarization can shift the wavelengths at which the directional scattering is achieved. We also explore the application of such an asymmetric nanoantenna as a tuneable routing element in a nanometer scale, suggesting applications in optical nanocircuitry.
Highlights
We propose a practical configuration of asymmetric dimers as a nanoscale routing element for electromagnetic radiation
We performed numerical simulations of the electromagnetic behavior of the light scattered from the nanoantenna using the finite-difference time-domain method (FDTD) method
We explore a platform with a dimer of silicon nanodisks placed on a silica substrate, in line with experimentally achievable geometric dimensions
Summary
The rotation of the scattering direction could be favourable for highly sensitive sensing schemes and nanoantennas in optical nanocircuits. We reveal that a dielectric nanodimer consisting of nanoparticles with different dimensions can scatter light directionally to either the right or left direction by tuning the incident wavelength. By carefully designing the dimer configuration, the direction of the scattered light becomes tuneable due to the interference between the dipoles excited in each particle. We carry out full theoretical calculations using an analytical dipole-dipole model to determine a favourable configuration for highly directional scattering tuneable via the incident wavelength. Directional control of the scattered light combined with low energy losses presented in this paper can facilitate the development of efficient sensors, waveguides and optical circuits at the nanometer scale
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