Vertical Second Harmonic Generation in Asymmetric Dielectric Nanoantennas
Davide Rocco, Carlo Gigli, Luca Carletti, Giuseppe Marino, M. A. Vincenti, Giuseppe Leo, Costantino De Angelis
Abstract
High-permittivity III-V semiconductor nanocavities have shown huge potential for enhanced nonlinear light-matter interactions at the nanoscale. In particular, Second Harmonic (SH) generation in AlGaAs nanoantennas can be extremely efficient; however, vertical emission is difficult to achieve, due to the zincblende χ <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">(2)</sup> tensor and epitaxially growth on (100) substrates. Here, we demonstrate that we can shape the second harmonic radiation pattern from a single AlGaAs nanostructure by exploiting a geometrical symmetry breaking optimization approach. The optimized design allows to redirect the SH signal toward the normal direction and to increase the SH power collection efficiency by 2 orders of magnitude in a small numerical aperture of 0.1 with respect to the symmetrical counterpart structure.