Figure 2: Scattering of a silicon nanoantenna sitting on a dielectric interface. | Nature Communications

Figure 2: Scattering of a silicon nanoantenna sitting on a dielectric interface.

From: Polarization-controlled directional scattering for nanoscopic position sensing

Figure 2

(a) Simulated scattering cross-section (linearly polarized Gaussian beam used for excitation) of a silicon sphere with radius r=92 nm; only the forward scattering efficiency into the angular region within the NA[0.95, 1.3] is considered to match the experimental detection scheme (see grey arcs in b,c, and far-field patterns in d,e). In the visible range, the nanosphere supports magnetic dipole (λMD≈670 nm), electric dipole (λED≈550 nm) and magnetic quadrupole (λMQ≈520 nm) resonances. At the excitation wavelength of λ=652 nm, the magnetic and electric dipole moments are π/2 out of phase with respect to each other. (b) Emission of a longitudinal electric dipole pz (see dashed red line) and a transverse magnetic dipole my (see black line) into the glass substrate. (c) In-phase far-field interference of pz and my results in strong directivity. Comparison of (d) a calculated far-field pattern (interference of pz and my) and (e) a measured back-focal-plane image, retrieved at an antenna position on the x axis 140 nm away from the centre of the beam.

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