Abstract
We designed AlGaAs-on-aluminium-oxide all-dielectric nanoantennas with magnetic dipole resonance at near-infrared wavelengths. These devices, shaped as cylinders of 400nm height and different radii, offer a few crucial advantages with respect to the silicon-on-insulator platform for operation around 1.55μm wavelength: absence of two-photon absorption, high χ((2)) nonlinearity, and the perspective of a monolithic integration with a laser. We analyzed volume χ((2)) nonlinear effects associated to a magnetic dipole resonance in these nanoantennas, and we predict second-harmonic generation exceeding 10(-3) efficiency with 1GW/cm(2) of pump intensity.
Highlights
Optical nanoantennas are nanoscale structures capable of efficiently collecting free-space light and confining it into subwavelength volumes far below the diffraction limit [1]
Even though plasmonic antennas have been employed for many applications, metals suffer from large resistive heating losses in the visible and near-infrared wavelength range, which limit device performance [8,9]
In order to illustrate the potential of AlGaAs cylinders for nonlinear nanophotonics, we investigated the Second-Harmonic Generation (SHG) phenomenon by using the nonlinear polarization induced by χ(2) as a source in COMSOL simulations
Summary
Optical nanoantennas are nanoscale structures capable of efficiently collecting free-space light and confining it into subwavelength volumes far below the diffraction limit [1]. In contrast to plasmonic antennas, the optical response of dielectric particles does not suffer from ohmic losses and can exhibit both strong electric and magnetic optical resonances at visible or near-IR wavelengths [11,12]. All-dielectric nanoantennas offer unique opportunities for the study of nonlinear effects due to very low losses in combination with multipolar characteristics of both electric and magnetic resonant optical modes [10]. To the best of our knowledge, the only investigations of the nonlinear optical response generated from a magnetic resonant optical mode in an all-dielectric antenna have been conducted on Si nanodisks [10,14]. At variance with indirect-bandgap Si, AlGaAs monolithic nanoantennas might benefit from the direct integration of diode lasers on a GaAs chip For all these reasons, here we study the linear and nonlinear scattering of AlGaAs-onaluminum-oxide monolithic nanodisks. Our results show that AlGaAs nanoantennas have a strong potential to enhance the SHG from all-dielectric nanostructures
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