Fig. 5: Deuterogenic effect in high-order SPhP vortex at ω = 900 cm⁻¹.

a–c, Amplitude and phase transmission sSNOM maps at ω = 900 cm⁻¹ for VG of L = −9 (a), L = −14 (b) and L = −19 (c) excited by RCP light. d–f, Experimental maps after FFT filtering. g–i, Corresponding simulated SPhP vortex where emission from all the edges of the VG is considered. j–l, Overlap integrals evaluated for the experimental data (top) and simulated data (bottom). The orange bars indicate the expected ℓ = −10 (j), ℓ = −15 (k) and ℓ = −20 (l). The grey bars indicate the values of ℓ at which we detect the coexistence of additional modes predicted from the deuterogenic effect. The insets show the false-colour SEM of the fabricated VG used in the experiments. Scale bar, 5 μm.