Optical detection in a ferromagnet

The detection of plane-polarized amplitude-modulated infrared laser radiation in a transparent yttrium-iron garnet ferromagnet at room temperature is performed experimentally. The nonlinear interaction mechanism is suggested. It is found that the magnitude and sign of the detected signal depend significantly on the magnetizing external magnetic field. The signal is observed when the magnetization of the ferromagnet approaches the saturated value. The measured dependence of the amplitude of the detected signal on the angle of polarization of the laser radiation with respect to the magnetization of the ferromagnetic sample supports the suggested nonlinearity mechanism. The largest nonlinearity appears when the magnetic field of the plane-polarized laser radiation is parallel to the magnetic moment of the magnetized ferromagnet.