Measurement of Birefringence Using the Magneto-Optical Modulator in the Magnetomechanical Resonance Mode

In order to detect magnetic linear birefringence of new materials, we have developed an installation using the magneto-optical modulator in the mode of magnetomechanical resonance. We have theoretically substantiated and experimentally applied radiation with phase-frequency dependencies of the Stokes vector on magnetomechanical resonance frequency for measuring magnetic linear birefringence. Our results demonstrate that the radiation in which the variable components of the Stokes vector have different initial phases after passing through the sample with linear birefringence leads to additional phase delays of the signal at the output of the photopolarimeter. As an example, the results of measurements of the magnetic linear birefringence in the film of yttrium iron garnet have been introduced. The minimum value of the linear birefringence which was measured in this experiment 0.018 deg. The advantage of the installation is the independence of the measurements results from the changes of the intensity in the optical system.