Nonlinear magneto-optical effects in cold atoms of ⁸⁷Rb

With laser-cooled cold ^87Rb atoms as a magneto-optical medium, a weak right circularly polarized probe field and frequency modulation technique are used to detect the magnetic distribution of the quadrupole field. A two-peak dispersion-like signal other than that of the usual nonlinear magneto-optical effect mentioned in other papers is obtained.