Resonant Magneto-Optical Rotation: New Twists in an Old Plot

Faraday e ect [1] is the rotation of the plane of linear light polarization by a medium in a magnetic eld applied in the direction of light propagation. In 1898, Macaluso and Corbino [2], studying absorption spectra of the alkali atoms in the presence of magnetic elds, discovered that the Faraday e ect in the vicinity of resonance absorption lines also had a distinct resonant character. The essence of the Macaluso-Corbino e ect can be illustrated by considering a simple case of a F = 1 ! F 0 = 0 transition { Figure 1. Linearly polarized light incident on the sample can be resolved into two counter-rotating circular components . In the absence of a magnetic eld, the jM = 1i sublevels are degenerate and the optical resonance frequencies for + and coincide. When a magnetic eld B is applied, however, the Zeeman shifts lead to a di erence between the resonance frequencies for the two circular polarizations of 2g B= h, where g is the Lande factor and is the Bohr magneton.