LAUSR

Vector beam propagation through a four-level tripod atomic system has been investigated. The three transitions of the tripod atomic system are coupled by a strong control field and the two constituent orthogonally polarized components of a weak probe vector beam. An external magnetic field induces anisotropy, creating a difference in the refractive indices of the two polarization components of the beam. This difference in refractive indices varies with the magnetic field strength and directly relates to the polarization orientation at any transverse plane. Thus, the transverse polarization structure can be rotated as desired with appropriate magnetic field strength. We further study the effect of nonlinearity and inhomogeneous broadening on the vector beam's polarization rotation. Therefore, the mechanism of efficient polarization control and manipulation of a vector beam can open up a new avenue for high-resolution microscopy and high-density optical communications.