Table 1 Comparison of chiral forces in a linearly polarised evanescent wave and the centre of a linearly polarised vortex and their relation to the spin decomposition
From: A decomposition of light’s spin angular momentum density
Evanescent wave from linearly polarised illumination | Centre of linearly polarised vortex beam | |
|---|---|---|
Chiral force \({{\bf{F}}}_{\text{chiral}}\) | \({\mathbf{F}}_{\text{chiral}}\neq{\mathbf{0}}\) (transverse) | \({\mathbf{F}}_{\text{chiral}}\neq{\mathbf{0}}\) (longitudinal) |
Type of chiral force | Spin recoil force \({{\bf{F}}}_{\text{chiral}}\propto {\bf{S}}\) negligible in small particles | Chiral pressure force \({{\bf{F}}}_{\text{chiral}}\propto {{\bf{s}}}_{\text{c}}\) dominant in small particles |
Total spin \({\bf{S}}={{\bf{s}}}_{\text{c}}+{{\bf{s}}}_{\text{p}}\) | \(\mathbf{S}\neq\mathbf{0}\) | \(\mathbf{S}=\mathbf{0}\) |
Canonical spin \({{\bf{s}}}_{\text{c}}\) | \({\mathbf{s}}_{\text{c}}={\mathbf{0}}\) | \({\mathbf{s}}_{\text{c}}\neq{\mathbf{0}}\) (longitudinal) |
Poynting spin \({{\bf{s}}}_{\text{p}}\) | \({\mathbf{s}}_{\text{p}}\neq{\mathbf{0}}\) (transverse) | \({{\bf{s}}}_{\text{p}}=-{{\bf{s}}}_{\text{c}}\) |
