Abstract

An isotropic medium, having atoms with m degenerate sublevels, when subjected to a magnetic field, can induce birefringence in the medium. As a result, the plane of polarization of a probe field rotates. This rotation is due to the fact that the magnetic field creates asymmetry between the susceptibilities χ± of the medium corresponding to the σ± component of the probe field. For a small absorption the rotation is given by θ = πk_pl(_χ−–_χ+); where ${\overrightarrow{k}}_P$ is the wave vector of the probe field and l is length of the cell used. We apply a coherent control field which modifies χ±. Therefore the rotation of probe polarization, due to magnetic field alone, can be controlled efficiently with the use of the control field [1]. We demonstrate this enhancement of the magneto-optical rotation (MOR) of a linearly polarized light, by doing detailed calculations on a four-level ⁴⁰Ca system with relevant transitions 4¹ S₀ ↔ 4¹P₁ ↔ 6¹ S₀. In a recent experiment [2], Wielandy and Gaeta have reported possibility of controlling polarization state of the probe using a polarized control field; however no magnetic field was used.

© 2000 IEEE