Multipole decomposition and second harmonic far-field distribution as a function of nanohelix loop radius; other geometric parameters of each helix are p = 200 nm, d = 100 nm, and N = 1, and multipole decomposition is done for (a) r = 20 nm, (b) r = 60 nm, and (c) r = 100 nm. (d) XY (left) and XZ (right) far-field distributions at 400 nm, for LCP and RCP excitations, and r = 20 nm (blue), r = 60 nm (green), and r = 100 nm (red). All polar plots are normalized to the maximum forward scattering for r = 100 nm and RCP excitation. (e) Electric field intensity at 400 nm in the xz-plane, when r = 100 nm nanohelix is excited from the top, at 800 nm, with RCP (left) and LCP (right).