Of elliptically polarized incident radiation, these are given by \[s_{0}^{0}=E_{1}^{0}+E_{2}^{0}\] \[s_{1}^{0}=E_{1}^{0}- E_{2}^{0}\] \[s_{2}^{0}=2\ \sqrt{E_{1}^{0}\ E_{2}^{0}}\ \cos \delta ^{0}\] \[s_{3}^{0}=2\ \sqrt{E_{1}^{0}\ E_{2}^{0}}\ \sin \delta ^{0}\] where E1^0 and E2^0 specify the irradiances of the incident light polarized with their electric vectors vibrating perpendicular and parallel to the scattering, respectively and δ 0 is the phase difference between these electric vectors.
See also: scattering matrix
Source:
PAC, 1983, 55, 931. 'Definitions, terminology and symbols in colloid and surface chemistry. Part 1.14: Light scattering (Provisional)' on page 933 (https://doi.org/10.1351/pac198355060931)