Figure 2
From: THz-photonics transceivers by all-dielectric phonon-polariton nonlinear nanoantennas
(a) The proposed AlGaAs nanodisk has radius r = 200 nm, and height h = 400 nm. Two plane waves in the near-infrared region, \(\lambda _1\) and \(\lambda _2\), are normally incident and generate through the bulk \(\chi ^{(2)}\) the nonlinear DFG signal. The schematic representation elucidates the THz generation by optical rectification of intra-pulse components of the incident infrared laser pump. (b) Scattering cross section decomposed in the multipolar contributions: electric (\(a_1\)), magnetic (\(b_1\)) dipole and electric (\(a_2\)), magnetic (\(b_2\)) quadrupole components, respectively. The gray area indicates the wavelength of the input beams. The inset shows the electric field enhancement inside the nanodisk at the MD resonance (black dotted line), in a plane (zx′) forming \(45^{\circ }\) with respect to the x and y axes. The red arrows highlight the circulating electric field. The plot is obtained by using COMSOL Multiphysics v5.5—https://www.comsol.com.
