Fig. 4: OAM multiplication for VG with different L values under LCP excitation.
From: Multiplication of the orbital angular momentum of phonon polaritons via sublinear dispersion
a, Shape of VGs with L = 1, 2, 3 and 7. b–e, Corresponding simulated amplitude and phase SPhP profiles at ω1 = 880 cm−1 (b), ω2 = 910 cm−1 (c) and ω3 = 924 cm−1 (d). For each row, we calculate the overlap integral as a function of frequency and OAM order, as shown in the maps in e. The maximum overlap is reached in all cases at frequencies of ω1, ω2 and ω3. The ℓ spacing between the different frequencies is L, confirming the multiplication of OAM order.
