Nonlinear electro- and magneto-optical effects related to Bennett structures

Optical pumping of an atomic sample with narrow-band light can create sub-Doppler features, known as Bennett structures, in the velocity distribution of state populations. In the presence of static magnetic or electric fields, the corresponding sub-Doppler features in the index of refraction can cause nonlinear optical rotation and induced ellipticity of resonant light propagating through the atomic medium. Physical mechanisms causing Bennett-structure-related nonlinear electroand magneto-optical effects are discussed in detail for transitions involving states with low angular momenta. Measurements of Bennett-structure-related nonlinear magnetooptical rotation and electric-field-induced ellipticity for the Rb D2 line are performed and compared to densitymatrix calculations. The latter effect can be used for measuring electric fields applied to atoms.