Table 1 Selection rules.

The orbital (first row), spin (second row), and total (third row) angular momentums of the excitation beams are summarized. The last row shows the angular momentums of the spoof LSPs observed in the experiment.

Gaussian
beam
Vortex beamVortex beam
OAM0+ħ−2ħ
SAM+ħ and −ħ+ħ and −ħ+ħ and −ħ
TAM+ħ and −ħ+2ħ0−3ħħ
Spoof
LSP
Dipole
(+ħ and −ħ)
Quadrupole
(+2ħ)
Hexapole
(−3ħ)
Dipole
(−ħ)