Abstract
Strong and directionally specific forward scattering from optical nanoantennas is of utmost importance for various applications in the broader context of photovoltaics and integrated light sources. Here, we outline a simple yet powerful design principle to perceive a nanoantenna that provides directional scattering into a higher index substrate based on the interference of multiple electric dipoles. A structural implementation of the electric dipole distribution is possible using plasmonic nanoparticles with a fairly simple geometry, i.e. two coupled rectangular nanoparticles, forming a dimer, on top of a substrate. The key to achieve directionality is to choose a sufficiently large size for the nanoparticles. This promotes the excitation of vertical electric dipole moments due to the bi-anisotropy of the nanoantenna. In turn, asymmetric scattering is obtained by ensuring the appropriate phase relation between the vertical electric dipole moments. The scattering strength and angular spread for an optimized nanoantenna can be shown to be broadband and robust against changes in the incidence angle. The scattering directionality is maintained even for an array configuration of the dimer. It only requires the preferred scattering direction of the isolated nanoantenna not to be prohibited by interference.
Highlights
Directional scattering of light plays an important role in a wide range of photonic technologies such as photovoltaics [1,2,3], quantum emitters [4,5], light emitting diodes [6,7,8], and optical wireless communication [9]
Summary In conclusion, we presented a simple design principle based on coupled dipolar sources to achieve strongly asymmetric directional scattering
We showed an asymmetric plasmonic dimer nanoantenna, which provides strong forward scattering cross sections with high directivity into a higher index medium around the Total Internal Reflection (TIR) angle
Summary
Directional scattering of light plays an important role in a wide range of photonic technologies such as photovoltaics [1,2,3], quantum emitters [4,5], light emitting diodes [6,7,8], and optical wireless communication [9]. The design of the asymmetric dimer nanoantenna is perceived by first considering the interference between multiple tangentially and normally oriented electric dipoles on top of a substrate. Our asymmetric dimer nanoantenna design was inferred by first considering the radiation pattern of electric dipolar line sources on top of the substrate.
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