Nonlinear magneto-optical effects in Ba vapor
  We report the first measurements of linear and nonlinear magneto-optical polarization rotation on an intercombination transition of Ba vapor (lambda= 791.1nm). We observe a maximum polarization rotation angle in Faraday configuration of 15mrad, accompanied by suppression of absorption. A theoretical treatment of the nonlinear Faraday effect in the limit of a strong interacting light field is developed. 
Irina Novikova, Alexander Khanbekyan, David Sarkisyan, George R. Welch