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All‐Optical Spin–Orbit Coupling of Light in Coherent Media Using Rotating Image
Author(s) -
Zhao Lu
Publication year - 2020
Publication title -
annalen der physik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.009
H-Index - 68
eISSN - 1521-3889
pISSN - 0003-3804
DOI - 10.1002/andp.201900371
Subject(s) - physics , electromagnetically induced transparency , spinor , paraxial approximation , spin–orbit interaction , coupling (piping) , spin (aerodynamics) , quantum mechanics , optics , thermodynamics , mechanical engineering , engineering , beam (structure)
The possibility of all‐optical spin–orbit coupling (SOC) of light is investigated based on a rotating spinor image traveling through an electromagnetically induced transparency (EIT) medium. It is shown that the paraxial evolution of the spinor image composed of two Laguerre–Gaussian (LG) modes with different frequencies can be analogous with the quantum dynamics of a spin‐1/2 particle with strong and tunable SOC governed by the Pauli equation, where the spin‐up and ‐down states have different effective masses. Using realistic EIT parameters with cold atoms, both the radial inhomogeneity of the strong control field and the atomic density distribution with comparable size are considered. The results confirm that the large group refractive index varying in the radial dimension mimicking the central potential can greatly enhance the spin–orbit interaction, leading to visible spatial quantization of the oppositely oriented spin states, equivalent to the two LG modes.